PCIE lanes for Nvme Pcie m.2

[LinussFAN-Noctua-]

Hello everyone!
I am a big noob regarding modern storage and I want to keep it short and simple so I am asking directly:
-ROG Crosshair VIII Hero https://www.asus.com/Motherboards/ROG-Crosshair-VIII-Hero/specifications/
-R9 3900x Cpu
-planing to buy 3080ti (or the rumored 3090 if under 1500$) which will 100% sure be a 16x pcie 4.0 Gpu (even if it turns out to still be pcie3.0, it's better to plan for the ''worst case'' for my pcie lanes).
Because I found contradicting information on this topic, it is unclear to me if:
1) will installing a nvme 4x pcie 3.0 m.2 SSD make the expensive GPU (or CPU??) any slower (even 1-2%)?
There would be only 1 nvme ssd.. all the rest storage are SATA.

1. using a 4x pcie 3.0 ssd, will I lose 4x 4.0 lanes anyway? (so it would make more sense\better use of the lanes to buy the new pcie 4.0 ssd?).
2. is it better for the m.2 pcie nvme ssd to run on the cpu pcie lanes or on the chipset (motherboard) pcie lanes? (I understand that my motherboard has some extra pcie lanes from chipset). Can I even decide\change on which lanes the ssd will run?
3. I have my eyes on the Samsung 970 and wanted to get the PRO but then I saw that the cheaper Evo is faster (IOPS and write speed).

How can this be? In this case, the shorter lifespan of the evo is worth it. I will probably go for 1tb evo plus than the planned 512gb PRO
https://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-970-evo-plus-nvme-m-2-1-tb-mz-v7s1t0b-am/#specs
https://www.samsung.com/us/computing/memory-storage/solid-state-drives/ssd-970-pro-nvme-m2-512gb-mz-v7p512bw/#specs

 

P.S: will I need a heatsink on this pcie ssd if I only use it for gaming( 90% of the time only read operation)?

Thank you all in advance!

[jj9987]

The GPUs today can not even fully saturate a 16x PCI Express Gen3 slot, the difference with 8x is very minimal. So I am quite sure 3080Ti will not bottleneck because of using a generation older PCI Express connection (the difference between 8x gen3 and 16x gen3 is double, 16x gen3 is equal to 8x gen4, 16x gen4 is double 16x gen3).

 

3900x has 20 PCI Express lanes (regardless of generation) - 16 lanes for the GPU and 4 lanes for a PCI Express NVMe SSD. In addition, it has 4 lanes for connection to the chipset. If you use two drives, the second will connect to the chipset, which incurs a slightly increased latency, but most likely nothing you will notice with actual usage.

 

Get the Evo Plus. Pro is quite a lot more expensive while giving so little gains. Unless you are doing heavy writes to the SSD (hundreds of gigabytes every day), they both will last a long time.

[schwellmo92]

#1 - the CPU's will have 20x PCI-E lanes so it will support a 4x NVMe and a 16x GPU both at PCI-E 4.0

 

#1 - don't really understand your question, but if you place a PCI-E 3.0 drive in that 4x slot it will still use those 4 PCI-E 4.0 lanes but just at 3.0 speed.

 

#2 - better to run on the CPU PCI-E lanes. The motherboard manual will say which slots are connected to the CPU vs chipset.

 

#3 - the evo plus is a newer drive hence it is faster, the PRO is a waste of money. There are other drives that are much cheaper for practically the same performance, I would look around as the evo plus is quite expensive.

 

[Enderman]

0) GPUs don't even use PCIe 3.0 x8 so it doesn't matter if it says it's a 16x 4.0 GPU, you can giv eit x8 or x4 with no performance loss.

 

1) yes it will still use x4, what PCIe 4.0 SSD are you talking about? They're all 3.0 as far as I know...

 

2) It won't make a difference, and probably depends on the motherboard.

 

3) The evo only has higher speeds at the beginning, once the cache is full the speeds drop to much lower than the 970 pro. That's why the Pro is more expensive and is called 'pro'.

 

4) If you're only gaming there is literally 0 benefit of using NVME at all, a regular sata SSD would perform the same.

 

5) Both SSDs will live longer than you do so you should not be concerned about their lifespan at all.

[Enderman]

3 minutes ago, schwellmo92 said:

#3 - the evo plus is a newer drive hence it is faster, the PRO is a waste of money. There are other drives that are much cheaper for practically the same performance, I would look around as the evo plus is quite expensive.

The Evo drives have a faster cache, once that fills up their speed drops.

[NewMaxx]

I replied to you in detail on the Tom's Hardware Forum so check that out.

[schwellmo92]

43 minutes ago, Enderman said:

The Evo drives have a faster cache, once that fills up their speed drops.

The cache is quite large though you'll likely never fill it unless you have like under 5% free capacity.

[NewMaxx]

Looks like he's talking about the 1TB 970 EVO Plus which has 6GB of static SLC and 36GB of dynamic SLC. Should be 12GB or more (total) up to 80% fill which is more than adequate. The EVO Plus in SLC mode is faster than the MLC-based 970 Pro, although I doubt he'd really push either drive.

[Enderman]

35 minutes ago, schwellmo92 said:

The cache is quite large though you'll likely never fill it unless you have like under 5% free capacity.

I'm not sure you know what a cache is or how it works.

It has nothing to do with how much the drive is filled.

 

The cache is where data is moved to/from before it is written to nand.

It looks to be about 32GB.

That means when you move more than 32GB at a time the speeds will drop to 1700MBps which is how fast it can write to the nand.

 

Either way, that's far more than anyone needs for gaming, so it's irrelevant to OP.

I'm just saying that you're wrong, the Pro model is more expensive because it can sustain its full speed writes continuously.

[Kilrah]

10 minutes ago, Enderman said:

I'm not sure you know what a cache is or how it works.

It has nothing to do with how much the drive is filled.

Commonly on QLC drives the amount of cache scales down as the drive fills since it not a dedicated area but just a part of the total advertised space that's used as cache when otherwise unused, so yes it can. 

[Enderman]

23 minutes ago, Kilrah said:

Commonly on QLC drives the amount of cache scales down as the drive fills since it not a dedicated area but just a part of the total advertised space that's used as cache when otherwise unused, so yes it can. 

First, that image was from a benchmark.

They do benchmarks on empty drives, not filled ones.

This is a best case scenario.

 

Second, there is a part of the cache that is not part of the drive space, it is just a cache.

There is a second cache that does get used as drive space, but you should never fill an SSD up that much anyway.

The point is, the 970 pro does not get reduced speeds during longer data tranfers.

[LinussFAN-Noctua-]

2 hours ago, Enderman said:

0) GPUs don't even use PCIe 3.0 x8 so it doesn't matter if it says it's a 16x 4.0 GPU, you can giv eit x8 or x4 with no performance loss.

 

1) yes it will still use x4, what PCIe 4.0 SSD are you talking about? They're all 3.0 as far as I know...

 

2) It won't make a difference, and probably depends on the motherboard.

 

3) The evo only has higher speeds at the beginning, once the cache is full the speeds drop to much lower than the 970 pro. That's why the Pro is more expensive and is called 'pro'.

 

4) If you're only gaming there is literally 0 benefit of using NVME at all, a regular sata SSD would perform the same.

 

5) Both SSDs will live longer than you do so you should not be concerned about their lifespan at all.

thank you for your reply and help!

this would be an example of pcie 4.0 ssd

https://www.corsair.com/de/de/Kategorien/Produkte/Datenspeicher/M-2-SSDs/Force-Series™-Gen-4-PCIe-NVMe-M-2-SSD/p/CSSD-F500GBMP600

 

I also want to go nvme because it's cable-free..(cables are a hassle)

I just want the loading times on Cyberpunk to be as fast as possible..and a fast storage would help with streaming textures (I have an ultrawide 3k monitor).I don't want any immersion-breaking texture pop-ins while driving\flying across the map-world. I just built this pc solely for Cyberpunk..and I expect to have an amazing, bottleneck free experience.

[LinussFAN-Noctua-]

THANK YOU ALL FOR YOUR THOUGHTS AND HELP!

So I will get the 970 Evo Plus (because as a games-ssd write speed or endurance isn't important)  without worrying about lanes and gpu getting slowed down.

If I could I would give ''best answer'' to all of you, but unfortunately I can only choose one.

Thank you all again!

[NewMaxx]

2 hours ago, Kilrah said:

Commonly on QLC drives the amount of cache scales down as the drive fills since it not a dedicated area but just a part of the total advertised space that's used as cache when otherwise unused, so yes it can. 

Not just QLC drives, TLC drives as well. There's both static and dynamic SLC and many drives have both, including the 970 EVO Plus. This cache is all part of the native flash run in single-bit mode, it is not actual SLC. Both types of SLC can exist outside the user-addressable space because flash is addressed logically but static SLC remains there for the lifetime of the device while dynamic will shift based on wear levels. There is no separate cache beyond this, the DRAM cache (which is far smaller anyway) is primarily used for metadata/mapping. Outside the SLC cache you will hit direct-to-TLC speeds (native flash, much slower than SLC mode) which has side effects like increasing chance of data loss since you're not using single-shot programming (this can be mitigated in some respects, e.g. a differential storage device to protect data-at-rest), although some drives lack this mode (the 660p being one). Drives like the 660p or those with larger dynamic caches will hit a lower performance state than this because all incoming data must go through the SLC cache and is bottlenecked by the copyback/folding speed of the SLC, in many cases because the drive must convert SLC to TLC, and there are latency penalties here as well.

 

There are some drives that have multiple types of memory, such as the H10 with 3D Xpoint + QLC, but that drive not only lacks dedicated SLC but requires two controllers. Future drives like the MiDrive might actually have a dedicated SLC portion, however that operates more like tiering than caching (hottest data goes to the faster memory) while current SLC caching is a write cache as the intent is to empty it to TLC/QLC as soon as possible, data is not retained there for reads.

[schwellmo92]

4 hours ago, Enderman said:

I'm not sure you know what a cache is or how it works.

It has nothing to do with how much the drive is filled.

 

The cache is where data is moved to/from before it is written to nand.

It looks to be about 32GB.

That means when you move more than 32GB at a time the speeds will drop to 1700MBps which is how fast it can write to the nand.

 

Either way, that's far more than anyone needs for gaming, so it's irrelevant to OP.

I'm just saying that you're wrong, the Pro model is more expensive because it can sustain its full speed writes continuously.

The SLC cache is dynamic based on free space and then gets compounded down to MLC/TLC/QLC further when the controller determines.

 

The Pro is more expensive because it uses MLC NAND so requires more NAND for the same capacity. The 970 evo plus uses TLC but has a better and newer controller.

[Enderman]

9 hours ago, LinussFAN-Noctua- said:

I also want to go nvme because it's cable-free..(cables are a hassle)

 

Ah that's a good reason.

I don't think you will notice any difference whether you get the MP600 or a 970 pro or a 970 evo plus.

Just pick the one you find cheapest, they are all extremely fast.

I personally only use samsung SSDs though, for reliability and endurance. I wish I could afford optane though.

 

If you have an unlimited budget and want the fastest SSD possible then you need to get the optane 905P.