Need a opinion for DDR5 RAM

[GanjajoggiBig]

So recently in my local repair shop a Ryzen 9 7900x3d (or 7950x3d both have the same box art) And a Asus TUF GAMING B650M-Plus WIFI and I planned to get those to prepare for my new GPU, but in terms of DDR5 Ram im rather clueless so I’ve gone to PC Part picker and found the TEAMGROUP T-Force Delta RGB 32 GB(2 x 16 GB) DDR5-7200 CL34 Memory, but im not sure if that is the right one since its a bit expensive

so I would kindly ask for a opinion/recommendation for DDR5 Ram, 

My budget would be Around 125 Euros, please make sure its available on amazon since I only have the money there, the cash I have on me is going to the mobo and cpu

[Blasty Blosty]

From my knowledge, the sweet spot of DDR5 is 32GB 6000MHz at CL30

 

@BahnStormer you seem like the guy for this

[BahnStormer]

Yes, DDR5 6000 CL=30 for the sweetspot. If you want to risk overspending for some limited gains, then try to get the CL lower, not the MT/sec higher.

 

MT/sec is fairly meaningless over 6000 due to the memory benefiting hugely from running in sync with various internal components on the CPU's - I can't recall the next theoretical sweetspot but, I would guess it would be the next multiple up on the 3000Mhz MEMCLK, so DDR5 12000MT/sec.... currently there are SOME that exist (DDR5-8000 CL38), but very expensive and the CPU's struggle to run those speeds in a stable manner, so very high risk for very, very little extra benefit.

Here's a recent detailed thread about it: for anybody else picking up on this - please note that these comments are very specifically about AMD AM5 (7000/8000/9000) systems:

 

ALSO: I would urge caution on ASUS B650M (or a lot of the B650M boards) as I seem to recall they had very weak VRM's, which start to run v hot on the 150W+ chips - 7800X3D would be okay, but 7700X (due to 0higher potential PBO boost speeds) or any of the 12/16 core chips due to higher expected VRM load.

Worth looking through this video: it looks like the "TUF Gaming B650M-E" is actually a really good one, not sure if this is the same as the "TUF Gaming B650M", I know ASUS had some really weak VRM's on some of their earlier B650M systems though and tweaked the names very slightly when they fixed them:
 

 

[GanjajoggiBig]

8 minutes ago, BahnStormer said:

Worth looking through this video: it looks like the "TUF Gaming B650M-E" is actually a really good one, not sure if this is the same as the "TUF Gaming B650M", I know ASUS had some really weak VRM's on some of their earlier B650M systems though:

Sadly I don’t really have choice without spending more money since the mobo is the only one they have in stock

[BahnStormer]

TL;DR

 

RAM: All the RAM availability is patchy, so you might need to wait on the cheaper suppliers to get stock... or wait for delivery from the US:

1) get the TeamGroup T-Create DDR5 6000 CL30 - I just bought some from Amazon two weeks ago for £99.90 (€119).

2) backup plan would be GSkill FlareX5 DDR5 6000 CL30, normally around £105 (so pushing closer to €130) and there was a couple of weeks' delay on those when I was last buying, which is why I went for the Teamgroup option.

 

Make sure it is the 6000MT/sec CL30 though... for €125 you should be able to get something though. Which Amazon supplier are you using (they vary between .nl/.fr, etc) and WATCH OUT: when they're out of stock and somebody usually tries to sell CL38 at the same price!

[BahnStormer]

Motherboards: if that is a crazy-good bundle that you have for the 7900X3D + B650M.... it might be because it was unstable running big all-core workloads... but it might still be worth getting for gaming and then just run it as a 7600X3D (set it in the BIOS to permanently "park" the 6x high clock cores and keep the 6x X3D core which will give you most of the gaming performance of a 7800X3D).

 

Just price it accordingly!  

[GanjajoggiBig]

1 hour ago, BahnStormer said:

Motherboards: if that is a crazy-good bundle that you have for the 7900X3D + B650M.... it might be because it was unstable running big all-core workloads... but it might still be worth getting for gaming and then just run it as a 7600X3D (set it in the BIOS to permanently "park" the 6x high clock cores and keep the 6x X3D core which will give you most of the gaming performance of a 7800X3D).

 

Just price it accordingly!  

Funnily enough they are still packaged, completely new, but I’ll remember that there is also the possibility that its the Ryzen 9 7950x3d

[BahnStormer]

I am a little worried: You have asked a lot of questions without saying anything about the rest of the components or exactly what games/tasks you need the PC for.

 

There is a very good reason those are critical questions in the "Please read before posting" part of this forum.

 

Why would you need a 7900X3D/7950X3D? Those CPU's are very bespoke use-cases*.... normally the 7800X3D is faster and will run happily on all but the worst B650 boards without too much stress.... dual CCD CPUs have some great benefits, but come with a LOT of drawbacks that I wish I'd known the first time I thought I was upgrading when I went from a 8 core to 12 core Ryzen! Hence why I devote hours most weeks to trying to educate people so they don't make the same expensive mistakes that I have.

 

I was just asking as if you are on any sort of a restricted budget, a 7900/7950X3D seems a strange choice.

 

*People who want to game and ALSO need very high capacity of CPU for video encoding or 3D rendering AND where they cannot do on their GPU. The 7800X3D can still do CPU-based code code compiling / 3D rendering / video editing.... just not quite as fast as the 7950X3D.... but for gaming the 7800X3D is normally faster and only needs a fraction of the supporting hardware (motherboard / PSU / cooling).

[BahnStormer]

I suspect the memory that you were looking at was this:

https://www.teamgroupinc.com/en/product-detail/memory/T-FORCE/delta-rgb-ddr5-black/delta-rgb-ddr5-black-FF3D532G7200HC34ADC01/

 

This would be great for an i7 build, but it is Intel XMP3, NOT AMD EXPO.... the good news is those are probably good chips with <9.4ns response time, but you will be left running the memory at DDR5 5200MT/sec unless you do the memory tuning manually... this is absolutely fine if you are up for some "fun" and a bit of a challenge... but the speed you will be aiming for is DDR5 6000MT/sec, CL30/CL29 as I don't think they will quite reach CL28 unless you win the silicon lottery.

Far better to buy good DDR5 6000MT/sec CL30 and it will get you 99% of the way there with a single "enable EXPO" option... no freezes / blue screens of deaths required... which you will probably see a lot of if you want to tune manually.

[brob]

https://de.pcpartpicker.com/product/sQfxFT/corsair-vengeance-32-gb-2-x-16-gb-ddr5-6000-cl30-memory-cmk32gx5m2b6000z30

 

https://de.pcpartpicker.com/product/Gk88TW/adata-xpg-lancer-blade-32-gb-2-x-16-gb-ddr5-6000-cl30-memory-ax5u6000c3016g-dtlabbk

 

https://de.pcpartpicker.com/product/mjt9TW/corsair-vengeance-rgb-32-gb-2-x-16-gb-ddr5-6000-cl30-memory-cmh32gx5m2b6000z30k

 

https://de.pcpartpicker.com/product/DgVmP6/gskill-trident-z5-neo-32-gb-2-x-16-gb-ddr5-6000-cl30-memory-f5-6000j3038f16gx2-tz5n

 

 

[GanjajoggiBig]

3 hours ago, BahnStormer said:

I am a little worried: You have asked a lot of questions without saying anything about the rest of the components or exactly what games/tasks you need the PC for.

 

i dont say a lot about the other componets because im set on still using them my case is a corsair 4000D airflow, my psu is a corsair cx750m semi modular my gpu (which i am preparing for with this upgrade) currently is a RX 570 but i plan to get a RX 7800 xt, and ive been asking questions since i want to upgrade my pc for games like pacific drive or minecraft with roughly 350 mods, and id really prefer a smooth and steady framerate for games, but the main use would be VR games since i really like them but need a lot of processing power to run smooth, also im currently  studiyng to become a IT Specialist in System integration so i think things like these are crucial for me to know

[BahnStormer]

Okay, thanks for clarifying: it was more to understand your use-case(s) and make sure you weren't buying something really inappropriate for your needs.

 

That said, the rest of the spec is fine - the GPU is getting a bit dated, but you're aiming for a nice step up with the 7800XT.

 

In terms of needing "lots of processing power", there are only a handful of games that benefit much from more than 6 cores and none that benefit from more than 8, unless you are doing something very CPU intensive in the background.... even Streaming these days is fine on a 7800X3D with a decent GPU.

 

There are slight downsides to going over 8 cores too: the max cores on one CCD (core complex die) is 8. If you have 12 cores, you effectively have 2x 6 core CPU's bolted together with a transfer layer "infinity fabric" between them... for the X3D chips, this is very important as the L3 cache only benefits one of the cores and the other half of the CPU is put in idle mode or "parked" to stop the game caching something one core and then stuttering while it transfers the cached data over from the other core.... this was a major problem in some games on AM4 CPU's like the 5900X/5950X.... the solution was to turn half the CPU off.

 

When a game is running the 7900X3D parks half and effectively becomes a 7600X3D and the 7950X3D effectively becomes a 7800X3D, EXCEPT there is still some overhead for managing that... so they're actually a fraction worse at gaming.

 

Unless you know that there is specific VR software that will still benefit from the 2nd CCD, I would urge you not to waste money when only half the CPU will likely be used most of the time and the other half will be costing you performance, not to forget the extra cash and heat! 

 

I know it seems to defy logic that the 12 core 7900X3D is almost the same price as a 7800X3D.... but the reason is because the 7800X3D has to be made from one perfect CCD.... while a 7900X3D is made from 2 CCD's where both had 2x failed cores (only 6 active) and couldn't make the standard to be a 7800X3D or 7700X.... so there's more supply... and in terms of demand: the 7800X3D is better for gaming and the 7900X3D only has a handful of use-cases.

 

I had a quick look on a couple of VR focussed chats and they seemed to recommend the 7800X3D too.... so unless there's some really custom software that you're running, I think you will be better saving the money and sticking with that.

[GanjajoggiBig]

7 hours ago, BahnStormer said:

Okay, thanks for clarifying: it was more to understand your use-case(s) and make sure you weren't buying something really inappropriate for your needs.

 

That said, the rest of the spec is fine - the GPU is getting a bit dated, but you're aiming for a nice step up with the 7800XT.

 

In terms of needing "lots of processing power", there are only a handful of games that benefit much from more than 6 cores and none that benefit from more than 8, unless you are doing something very CPU intensive in the background.... even Streaming these days is fine on a 7800X3D with a decent GPU.

 

There are slight downsides to going over 8 cores too: the max cores on one CCD (core complex die) is 8. If you have 12 cores, you effectively have 2x 6 core CPU's bolted together with a transfer layer "infinity fabric" between them... for the X3D chips, this is very important as the L3 cache only benefits one of the cores and the other half of the CPU is put in idle mode or "parked" to stop the game caching something one core and then stuttering while it transfers the cached data over from the other core.... this was a major problem in some games on AM4 CPU's like the 5900X/5950X.... the solution was to turn half the CPU off.

 

When a game is running the 7900X3D parks half and effectively becomes a 7600X3D and the 7950X3D effectively becomes a 7800X3D, EXCEPT there is still some overhead for managing that... so they're actually a fraction worse at gaming.

 

Unless you know that there is specific VR software that will still benefit from the 2nd CCD, I would urge you not to waste money when only half the CPU will likely be used most of the time and the other half will be costing you performance, not to forget the extra cash and heat! 

 

I know it seems to defy logic that the 12 core 7900X3D is almost the same price as a 7800X3D.... but the reason is because the 7800X3D has to be made from one perfect CCD.... while a 7900X3D is made from 2 CCD's where both had 2x failed cores (only 6 active) and couldn't make the standard to be a 7800X3D or 7700X.... so there's more supply... and in terms of demand: the 7800X3D is better for gaming and the 7900X3D only has a handful of use-cases.

 

I had a quick look on a couple of VR focussed chats and they seemed to recommend the 7800X3D too.... so unless there's some really custom software that you're running, I think you will be better saving the money and sticking with that.

im being honest, my money saving method is that i hope to get both the mobo and the cpu for 480 at the shop, that alone would be a very cheap deal considering after my research i found the cpu alone to be priced at 500, and as i said befor i really dont have an idea which one it is, its only the standard box with the same markings as a x3d chip, im not entirely sure, since the only reference i can use is the box, and no i dont use custom software, getting these parts would simply be cheaper than ordering from amazon, mostly because my budget is very tight

[BahnStormer]

Please check that you will be allowed to verify what is in the box and return the parts if you aren't happy..... that box is meaningless if it doesn't contain

 

At home I have a Ryzen 7 2700X box.... with a 1600X in it, a Ryzen 9 5900X box with a 2700X in it, a Ryzen 7 7800X3D box with nothing in it.... you get the idea.... but if I went to sell them at a 2nd hand store, I would probably just take the whole lot over in the current state.

 

Plus people are going to pretty extreme lengths (way beyond just the box!!!) to sell people unusable junk, not to mention CPU's that work, but are branded incorrectly - where you'll only know once they won't perform.

 

 

 

[GanjajoggiBig]

12 minutes ago, BahnStormer said:

Please check that you will be allowed to verify what is in the box and return the parts if you aren't happy..... that box is meaningless if it doesn't contain

 

At home I have a Ryzen 7 2700X box.... with a 1600X in it, a Ryzen 9 5900X box with a 2700X in it, a Ryzen 7 7800X3D box with nothing in it.... you get the idea.... but if I went to sell them at a 2nd hand store, I would probably just take the whole lot over in the current state.

 

Plus people are going to pretty extreme lengths (way beyond just the box!!!) to sell people unusable junk, not to mention CPU's that work, but are branded incorrectly - where you'll only know once they won't perform.

 

 

 

ive worked at the said store before and as far as i know they arent dirty scammers, ive even bought my monitor there an

AOC C27G1 27.0" 1920 x 1080 144 Hz Curved Monitor and its worked like a dream so far, my mother bought her laptop there too and they even gave her a replacement bettery if the one inside the laptop loses a lot of its capacity

 

12 minutes ago, BahnStormer said:

Plus people are going to pretty extreme lengths (way beyond just the box!!!) to sell people unusable junk, not to mention CPU's that work, but are branded incorrectly - where you'll only know once they won't perform.

also im pretty sure you can inspect in the device manager if its the wrong cpu, since the name is hardcoded to be shown in device manager

[BahnStormer]

12 hours ago, GanjajoggiBig said:

ive worked at the said store before and as far as i know they arent dirty scammers

okay - probably worth trusting them then... if the parts are bad, I'm guessing they would let you return them then

 

12 hours ago, GanjajoggiBig said:

also im pretty sure you can inspect in the device manager if its the wrong cpu

this can be flashed into the fake CPUs... normally they don't even bother with that though as they'd have to give you a working chip (even if it is a 7500F).

[GanjajoggiBig]

On 9/17/2024 at 9:40 PM, BahnStormer said:

okay - probably worth trusting them then... if the parts are bad, I'm guessing they would let you return them then

 

this can be flashed into the fake CPUs... normally they don't even bother with that though as they'd have to give you a working chip (even if it is a 7500F).

bit off topic but you seem to know your cpu's so im gonna ask, since the 7900x3d is seperated into two 6 core pairs could one act as a gpu and the other as cpu?

 

[BahnStormer]

2 hours ago, GanjajoggiBig said:

bit off topic but you seem to know your cpu's so im gonna ask, since the 7900x3d is seperated into two 6 core pairs could one act as a gpu and the other as cpu?

 

TL;DR - no, it doesn't work like that at all.

 

I haven't tested this in depth myself, but I'm fairly certain that the architecture means that the iGPU part of the 7000 series is complete independent as they all say "2 cores" and that's not part of the CPU core count... so you'd get the same gaming performance from a 7600X3D as a 7900X3D if you were to try using that as a gaming output.... the higher clocked non 3D V-cache side of the CPU is just parked for gaming to avoid the X-CCD latency issues.

 

Don't get me wrong - the onboard Radeon "GPU" side of the 7000 series does the basics very nicely: anything up to and including high res media playback, but don't buy it thinking you're getting something comparable to a gaming GPU.

 

If it anything like the GPU on my 7840HS (laptop), I think they're fine for 1080P low/medium, but nothing much beyond that if you want >30FPS.... I think they benchmark somewhere between a GTX1050 and GTX1050Ti... even the hot garbage version of the RX6000 series (RX6400) is apparent 4x faster!

 

I've got my two extra screen (1200P and a 1440P) running on those slots, so they're plugged into the motherboard HDMI and DP and appear as "Radeon" devices, but my gaming is coming from a separate dedicated GPU.

[GanjajoggiBig]

15 minutes ago, BahnStormer said:

If it anything like the GPU on my 7840HS (laptop), I think they're fine for 1080P low/medium, but nothing much beyond that if you want >30FPS.... I think they benchmark somewhere between a GTX1050 and GTX1050Ti... even the hot garbage version of the RX6000 series (RX6400) is apparent 4x faster!

so would it be better than a rx 570 8GB? on 2 1080p screens?

 

[BahnStormer]

1 hour ago, GanjajoggiBig said:

so would it be better than a rx 570 8GB? on 2 1080p screens?

 

RX570 is faster.

 

Game on the RX570 and use the onboard for your 2nd screen.

[SpecTre12345]

Corsair, Crucial, or Team Group!

[BahnStormer]

Preference for me has always been GSkill first.... but then I've also got active systems in the house with Teamgroup, Crucial and Corsiar too.... and from what I've seen, all the mainstream brand DDR5 RAM is all SKHynix underneath and all perform VERY much the same if you're just going to run them at EXPO speeds.

 

The important thing for AM5 is really that you buy the ones with EXPO profile of 6000MT/sec CL30.

[SpecTre12345]

Just now, BahnStormer said:

Preference for me has always been GSkill first.... but then I've also got active systems in the house with Teamgroup, Crucial and Corsiar too.... and from what I've seen the DDR5 systems are pretty much all SKHynix underneath and all perform VERY much the same if you're just going to run them at EXPO speeds.

 

The important thing for AM6 is really that you buy the ones with EXPO profile of 6000MT/sec CL30.

 

Stop recommending DDR5 6000 MT/s. Ryzen has proven to handle 8000MHz. And on top of that the myths that it doesn't do anything are nothing more than mythos. If you want smoother gameplay and better frame_times you have to go faster memory, period.

[BahnStormer]

15 hours ago, SpecTre12345 said:

 

Stop recommending DDR5 6000 MT/s. Ryzen has proven to handle 8000MHz. And on top of that the myths that it doesn't do anything are nothing more than mythos. If you want smoother gameplay and better frame_times you have to go faster memory, period.

Okay - I'm guessing this is just trolling for the sake of it... but I'll just correct your statement, in case somebody picks up on this thread and thinks you were being serious.

 

I am just offering people advice based on reasonably sound electronic engineering understanding and lots of well proven research.

 

Please don't tell people that "more Mhz = better" as that doesn't fit with the fundamentals of the CPU and internal memory controller on any AMD system in the last 5+ years (certainly Zen2 onwards).

 

I think you might have confused a few things.

 

I'll try to give you some credit in that your advice does have some truth with the way the Intel memory controllers work - with these, it makes sense to aim for high MT/sec memory.... I haven't looked at the exact specs, but there appears to be an improvement at each incremental increase in MT/sec rating, provided the CAS latency doesn't climb up too high at the same time.

 

AMD memory controllers don't work in the same way - you need to match the memory speed to the memory controller speed to get optimal performance out of the memory: I can't recall the exact numbers, but for Zen2 it was around 1500-1600Mhz, Zen3 1800Mhz and Zen4+Zen5 it is definitely 3000Mhz.

 

On that note: I think you've also mistaken Mhz for MT/sec.... I can almost guarantee you that no AM5 system can handle RAM at 8000Mhz and be stable.... remember that DDR stands for DOUBLE data rate... this means that the memory transfers happen on the rising AND falling edge of the signal, so 8000Mhz = 16000MT/sec!

 

Assuming you meant 8000MT/sec (4000Mhz), then yes - AM5 is able to run this, but it does NOT mean that you should as it will only be better in some very niche synthetic benchmarks or with extremely expensive low latency RAM and then only a very tiny fraction better.

 

Most of the time, it is a complete waste to buy memory much faster than 3000Mhz (6000MT/sec): the internal memory controller speed in Zen4 + Zen5 is 3000Mhz. If you keep this at a 1:1 ratio with the RAM, you will see optimal memory performance.

 

With DDR5 8000MT/sec (4000Mhz), it means that the memory would have the data ready 33% earlier than than the memory controller would be able to process it.

 

This in itself isn't a problem: if you're running DDR5 8000MT/sec CL30 - it would probably perform a few percent better than DDR5 6000 CL30.... but we're talking a small advantage and DDR5 8000MT/sec CL30 is not cheap... if you can even find it?

 

I know DDR5 8000 CL38 is more than double the price of a good DDR5 6000 CL30 kit at current prices.

 

The problem comes when people blindly buy "big number better" DDR5, but also try to save money, they will probably end up with a higher CAS latency.... The Column Address Strobe cycle wait time (aka "CAS latency" or "CL") is the number of cycles that you need to divide the Mhz rating by to see the performance of the underlying memory chip; the CL is the number that you want to have LOWER.

 

Looking at the theoretical performance: we're talking about 9.5ns response (DDR5 8000 CL38) versus 10ns (DDR5 6000 CL30), which will only be measurable in synthetic benchmarks that focus on pure memory throughput - possibly showing a 5% benefit to the DDR5 8000MT/sec memory that cost twice as much.

 

The gaming performance of that DDR5 8000 actually being more like 12.67ns once you allow for the memory controller running at 3000Mhz and the memory operating on a 38 cycle CAS latency, so it will intermittently perform nearly 30% slower   

 

This is the problem that you see when the RAM gets significantly out of sync with the memory controller and the CL is high: the avg frame rate doesn't tank immediately, so people don't realise that it's their "big number better" memory that is causing the problem.

 

If you look carefully, you will see that the 1% and 0.1% lows drop dramatically, which can make a game feel a lot more jumpy than the avg frame rate would indicate. Synthetic benchmarks and average frame rates say it is okay, but the 0.1% lows give it away.

 

Here's a prime example....

 

 

 

In practice, an X3D chip (with lots of L3 cache) will smooth out this inconsistent memory performance from the high Mhz, high CAS latency RAM... but it makes a noticeable difference for people running lower-end non-X3D chips, hence why I'm trying to advise them to buy memory that gives them optimal gaming performance for their money.

[starsmine]

1 hour ago, BahnStormer said:

Okay - I'm guessing this is just trolling for the sake of it... but I'll just correct your statement, in case somebody picks up on this thread and thinks you were being serious.

 

I am just offering people advice based on reasonably sound electronic engineering understanding and lots of well proven research.

 

Please don't tell people that "more Mhz = better" as that doesn't fit with the fundamentals of the CPU and internal memory controller on any AMD system in the last 5+ years (certainly Zen2 onwards).

 

I think you might have confused a few things.

 

I'll try to give you some credit in that your advice does have some truth with the way the Intel memory controllers work - with these, it makes sense to aim for high MT/sec memory.... I haven't looked at the exact specs, but there appears to be an improvement at each incremental increase in MT/sec rating, provided the CAS latency doesn't climb up too high at the same time.

 

AMD memory controllers don't work in the same way - you need to match the memory speed to the memory controller speed to get optimal performance out of the memory: I can't recall the exact numbers, but for Zen2 it was around 1500-1600Mhz, Zen3 1800Mhz and Zen4+Zen5 it is definitely 3000Mhz.

 

On that note: I think you've also mistaken Mhz for MT/sec.... I can almost guarantee you that no AM5 system can handle RAM at 8000Mhz and be stable.... remember that DDR stands for DOUBLE data rate... this means that the memory transfers happen on the rising AND falling edge of the signal, so 8000Mhz = 16000MT/sec!

 

Assuming you meant 8000MT/sec (4000Mhz), then yes - AM5 is able to run this, but it does NOT meant that you should as it will only be better in some very niche synthetic benchmarks or with extremely expensive low latency RAM and then only a very tiny fraction better.

 

Most of the time, it is a complete waste to buy memory much faster than 3000Mhz (6000MT/sec): the internal memory controller speed in Zen4 + Zen5 is 3000Mhz. If you keep this at a 1:1 ratio with the RAM, you will see optimal memory performance.

 

With DDR5 8000MT/sec (4000Mhz), it means that the memory would have the data ready 33% earlier than than the memory controller would be able to process it.

 

This in itself isn't a problem: if you're running DDR5 8000MT/sec CL30 - it would probably perform a few percent better than DDR5 6000 CL30.... but we're talking a small advantage and DDR5 8000MT/sec CL30 is not cheap... if you can even find it?

 

I know DDR5 8000 CL38 is more than double the price of a good DDR5 6000 CL30 kit at current prices.

 

The problem comes when people blindly buy "big number better" DDR5, but also try to save money, they will probably end up with a higher CAS latency.... The Column Address Strobe cycle wait time (aka "CAS latency" or "CL") is the number of cycles that you need to divide the Mhz rating by to see the performance of the underlying memory chip; the CL is the number that you want to have LOWER.

 

Looking at the theoretical performance: we're talking about 9.5ns response (DDR5 8000 CL38) versus 10ns (DDR5 6000 CL30), which will only be measurable in synthetic benchmarks that focus on pure memory throughput - possibly showing a 5% benefit to the DDR5 8000MT/sec memory that cost twice as much.

 

The gaming performance of that DDR5 8000 actually being more like 12.67ns once you allow for the memory controller running at 3000Mhz and the memory operating on a 38 cycle CAS latency, so it will intermittently perform nearly 30% slower   

 

This is the problem that you see when the RAM gets significantly out of sync with the memory controller and the CL is high: the avg frame rate doesn't tank immediately, so people don't realise that it's their "big number better" memory that is causing the problem.

 

If you look carefully, you will see that the 1% and 0.1% lows drop dramatically, which can make a game feel a lot more jumpy than the avg frame rate would indicate. Synthetic benchmarks and average frame rates say it is okay, but the 0.1% lows give it away.

 

Here's a prime example....

 

 

 

In practice, an X3D chip (with lots of L3 cache) will smooth out this inconsistent memory performance from the high Mhz, high CAS latency RAM... but it makes a noticeable difference for people running non-X3D chips, hence why I'm trying to advise them to buy memory that gives them optimal gaming performance for their money.

I honestly didnt know anyone had gotten 8000MT/s stable on zen 4.