Will my AM5 system give me trouble booting up with DDR5 7200 48GB (2x24GB)?

[AnimeMangaGamer]

I recently changed my platform back to AMD from Intel, with 9700X and B650E-F mobo and was wondering if the new replacement kit I just ordered will cause boot up issues before I could even lower the speed to acceptable 6000-6400 speed:

G.SKILL Trident Z5 Royal Series 48GB (2 x 24GB) 288-Pin PC RAM DDR5 7200 (PC5 57600) Desktop Memory Model F5-7200J3646F24GX2-TR5S

Cause before this I tried to do 4x sticks of 16GB DDR5 6000 and it wouldn't even boot up I keep getting the consistent orange led memory ram error. I didn't know back then but I just learned recently that AM5 due to memory controller limits, doesn't accept 4 sticks well like it used to in DDR4. So I solve that by just leaving 2 slots vacant and only installed 2 sticks or 32GB dual rank 6000. If I somehow forced the 4 sticks and miraculously managed to boot into windows they all ran at reduced 3600MHz but once I restart the PC it will result in unbootable state again with orange led memory ram error and I'd have to clear CMOS all over again and force boot my into windows from the BIOS.

I just hope these 2 sticks will boot just fine when I install them since the CMOS reset on this motherboard is at a very inconvenient location right at the very bottom of the board:
 

And as you can see it's a little busy inside my build:
 

 

With a rigid custom loop, it's not really easy to move things out of the way to access the CMOS reset pins. The GPU is on a vertical mount sitting on 2x 120x120 metal fan brackets with spacers for clearance so that the weight of gpu doesn't push the brackets down to touch the 15mm slim 120mm fans underneath it and then underneath those 3 slim fans is a slim XSPC TX360 radiator (this is my secondary 360mm radiator in this loop, the primary rad is a EKWB PE360 mounted on the top of the case not shown in the pic)

As you can see behind the GPU it's not even the riser cable that's in the way it's the radiator+slim fans on the bottom and all the cables tucked down there is the problem.

 

Here is a pick without the stuff in the way, the main problem is the motherboard sits with a millimeter of clearance from touching the bottom ceiling and my gpu vertical mount+radiator+fans are in the way of accessing those pins. So it's gonna be a huge hassle to clear CMOS because this motherboard model doesn't have a convenient clear button on the rear i/o. I'd have to drain my loop and disconnect everything which is something I'm trying to avoid doing.

Why are you changing it? Why not just leave the 32GB (2x16GB) 6000 right in there right now?

Because I had 64GB ram before and 32GB isn't enough and also the new ram is pretty  (I used to have DDR4 Trident Z Royals but for they weren't available yet when I upgraded to DDR5 so now I can switch back to them) 

 

[Tetras]

You'll probably be okay, 4 sticks is a special case, but how old is the BIOS likely to be? B650 boards were released before 24/48 was widely available and most will have notes in the BIOS docs specifically for these sticks.

[Millios]

Yeeaaaah CL30 6000mhz is the most you can get ddr5 on am5 and be stable with

Maybe cl32 6400mhz if you get lucky with the CPU silicone

 

7200mhz wont be stable if it boots at all (have seen testimonies of this)

Out the box they should be slower and via bios set them to the speeds I mentioned above and it should be fine

[AnimeMangaGamer]

24 minutes ago, Tetras said:

You'll probably be okay, 4 sticks is a special case, but how old is the BIOS likely to be? B650 boards were released before 24/48 was widely available and most will have notes in the BIOS docs specifically for these sticks.

I updated the motherboard firmware/bios even before I started the upgrade so I hope it works.

You're words are reassuring and I really hope I can just boot it up and if need to I'll lower the speed in the BIOS. As long as I don't need to clear the CMOS that'll save me hours of work.

[AnimeMangaGamer]

27 minutes ago, Millios said:

Yeeaaaah CL30 6000mhz is the most you can get ddr5 on am5 and be stable with

Maybe cl32 6400mhz if you get lucky with the CPU silicone

 

7200mhz wont be stable if it boots at all (have seen testimonies of this)

Out the box they should be slower and via bios set them to the speeds I mentioned above and it should be fine

Yeah I completely understand, I just hope it lets me boot up to the BIOS in order to even change the values to acceptable frequencies. Cause if I need to clear the CMOS in order to reach the BIOS, welp.. 

I guess I'll report back when the new RAM kit arrives.

[Tetras]

5 minutes ago, AnimeMangaGamer said:

I updated the motherboard firmware/bios even before I started the upgrade so I hope it works.

I expect you'll be fine, there's a fair few updates that sound relevant to you there.

[AnimeMangaGamer]

3 minutes ago, Tetras said:

I expect you'll be fine, there's a fair few updates that sound relevant to you there.

Thank you for checking, I'll report back and update once I receive the new kit.

[RONOTHAN##]

2x24GB does work just fine on AM5 assuming the BIOS is relatively new (if it can boot a 9700X, it's more than new enough), 7200 is going to be the problem. It can work (it probably will just boot), but the problem is that it will be quite slow. AM5 has two memory controller modes, 1:1 and 2:1 mode, where 2:1 mode runs the memory controller at half the speed of the memory, allowing it to hit higher speeds at the expense of memory latency. 7200MT/s is firmly in the range where 2:1 mode is a necessecity, and the latency penalty from 2:1 mode is high enough that you don't actually get any performance benefit from the higher clocked memory. Unless you do one of the handful of tasks that actually benefits from 2:1 mode, you're almost certainly going to be better off dropping your memory to something like 6000 CL30 and running it in 1:1 mode. 

 

2:1 mode can also give weird stability issues at some points, so it really should be avoided if possible. 

[cmndr]

AM5 struggles with more than 2 sticks at this time.

It also struggles to go much past 6000MHz at this time. Unless you want to cut the memory controller speed in half... in which case you end up with a performance hit more often than not. 

 

I would personally target "around" 6000MHz but focus on getting good timings with a 1:1 ratio. 

[AnimeMangaGamer]

On 4/21/2025 at 12:12 PM, RONOTHAN## said:

2x24GB does work just fine on AM5 assuming the BIOS is relatively new (if it can boot a 9700X, it's more than new enough), 7200 is going to be the problem. It can work (it probably will just boot), but the problem is that it will be quite slow. AM5 has two memory controller modes, 1:1 and 2:1 mode, where 2:1 mode runs the memory controller at half the speed of the memory, allowing it to hit higher speeds at the expense of memory latency. 7200MT/s is firmly in the range where 2:1 mode is a necessecity, and the latency penalty from 2:1 mode is high enough that you don't actually get any performance benefit from the higher clocked memory. Unless you do one of the handful of tasks that actually benefits from 2:1 mode, you're almost certainly going to be better off dropping your memory to something like 6000 CL30 and running it in 1:1 mode. 

 

2:1 mode can also give weird stability issues at some points, so it really should be avoided if possible. 

Oh thank you so much for providing more in depth insight, yeah I think it might give me some issues because this specific kit I bought it is an Intel XMP kit:

Honestly I don't think I need or want it to run the full speed I'm perfectly happy with just 6000.. as I c

https://www.gskill.com/product/165/418/1716793929/F5-7200J3646F24GX2-TR5S

You mentioned to drop the CAS Latency to CL30 would that be possible? This kit is CL36 like my previous ones. Isn't the CAS Latency like a quality binning thing with memory ram? like silicon lottery with CPUs? I'm sorry I'm inexperienced when it comes to tinkering BIOS settings, I never manually overclock my CPU's or memory in the pas. I only rely on XMP, EXPO, PBO, etc..
 

The last thing I did was undervolting (negative offset via SVID voltage) the 13900K and 14900KF to avoid the temps hitting the red line on HWInfo64; it was also thermal throttling. For just gaming I don't think I ever needed to overclock the CPU realistically. The GPU though I do manually overclock by adding a few more MHz and memory clocks. 

 

On 4/21/2025 at 1:39 PM, cmndr said:

AM5 struggles with more than 2 sticks at this time.

It also struggles to go much past 6000MHz at this time. Unless you want to cut the memory controller speed in half... in which case you end up with a performance hit more often than not. 

 

I would personally target "around" 6000MHz but focus on getting good timings with a 1:1 ratio. 

At the moment I have a temporary placeholder while I'm waiting for the new RAM (since I already sold my 64GB 6000 kit [4x16GB kit]), It's currently a DDR5 6400MHz C36 AMD EXPO kit and it seems to be running at 6400 just fine after I enabled EXPO on BIOS. Should I try to run 6400 when my new kit arrives or should I not even bother since it's an XMP kit not an EXPO kit? I think I might just do 6000 if that is the sweet spot since that's what I've been using for 2 yrs now.

[RONOTHAN##]

1 hour ago, AnimeMangaGamer said:

You mentioned to drop the CAS Latency to CL30 would that be possible? This kit is CL36 like my previous ones. Isn't the CAS Latency like a quality binning thing with memory ram? like silicon lottery with CPUs? I'm sorry I'm inexperienced when it comes to tinkering BIOS settings, I never manually overclock my CPU's or memory in the pas. I only rely on XMP, EXPO, PBO, etc..

Yes and no. CAS latency (as well as any other timing) is measured in clock cycles, so while you're changing the CL value, since you're changing the frequency an equal amount you aren't actually taking the amount of time a CAS operation takes. The actual amount of time is where the silicon lottery comes into play, so as long as you're adjusting both equally, you don't actually go outside the rated limits of the kit. It gets weird when you drop the frequency down a ton, since some kits do have a floor for the timings (I.E. below 20 the kit stops functioning), though 30 is going to be well above that. 

 

1 hour ago, AnimeMangaGamer said:

Should I try to run 6400 when my new kit arrives or should I not even bother since it's an XMP kit not an EXPO kit?

XMP vs. EXPO doesn't matter outside of the initial AM5 BIOS revisions. They're two sides of the same coin, most of the differences are just marketing. 

 

As for running 6400, it wouldn't hurt to try. The worst thing that will happen is that it won't boot and you need to Clear CMOS to get it to work. Most Ryzen 9000 series chips should do 6400 in 1:1 mode, though it's not all of them. Just make sure to set 1:1 mode as otherwise you're giving up a fair bit of performance. 

 

 

Your current kit is probably running in 2:1 mode, so you might get more performance if you drop your memory speed slightly to get it into 1:1 mode. 

[cmndr]

2 hours ago, AnimeMangaGamer said:

At the moment I have a temporary placeholder while I'm waiting for the new RAM (since I already sold my 64GB 6000 kit [4x16GB kit]), It's currently a DDR5 6400MHz C36 AMD EXPO kit and it seems to be running at 6400 just fine after I enabled EXPO on BIOS. Should I try to run 6400 when my new kit arrives or should I not even bother since it's an XMP kit not an EXPO kit? I think I might just do 6000 if that is the sweet spot since that's what I've been using for 2 yrs now.

warning up front - I've gotten "lazy" about doing upgrades. I haven't jumped onto AM5 yet. 

 

I wouldn't worry a ton about XMP vs EXPO. 6000-6400 is probably fine. If it "just works"  that's great and likely "good enough" - just verify that everything is running 1:1
If it's like AM4 and modern intel platforms... get to a "fast enough" frequency and then focus on timings AND subtimings. 

 

I would try to find a guide online that touches on your specific platform. The specifics change each generation, but the overall concepts stay the same.

This is fairly similar to tuning LGA775 roughly 20 years ago... run 1:1, tune timings, don't go OFF of 1:1 unless you're really able to get very high speeds (which could happen once RAM gets faster but only if motherboards improve a lot or we switch to a different memory set up - e.g. CAMM - but it isn't happening with today's kits)