Bought an XMP 3.0 ram kit for an AM5 MB, how bad is this?
Posted by Yestum@reddit | buildapc | View on Reddit | 8 comments
I have finished receiving all the components I wanted for my first PC build. And I couldn't be more excited about it. But something has been worrying me and that is that when I checked the RAM box I noticed that it mentioned that it was Intel XMP 3.0 Ready, which concerned me since my motherboard is an AM5 which uses Expo. I hadn't realized that the memory was of this type since according to PCPartPicker the memory is compatible with the build and it didn’t mention at first glance that it was and intel XMP kit. I understand that they will indeed be compatible but the speeds that the memory mentions will not be reached and it will possibly remain at 4800 MT which is the base speed for DDR5. My question is, is there any way to get a speed close to that mentioned by the RAM kit in a stable way? And if the board I have is compatible with XMP 3.0? The components I have are:
Ram: G.Skill Trident Z5 RGB 64 GB (2 x 32 GB) DDR5-6400 CL32
MB: MSI MAG B650 TOMAHAWK WIFI ATX AM5
CPU: AMD Ryzen 7 7800X3D
aminy23@reddit
First XMP & EXPO are both super primitive and basic technology. It's not something fancy or high tech.
95% of what it does it tells the motherboard the RAM is:
It's like a digital Post-It note. Most AMD boards can read both EXPO and XMP.
Now the problem here isn't EXPO or XMP, but rather the 7800X3D is 100% guaranteed to work with RAM up to 5200.
Now using made up numbers to reflect my experiences with builds, advice, and feedback: * DDR5-5600 - 99.9% chance of working, never saw an issue with it, and AMD later rated the same memory controllers for this speed * DDR5-5800 - 99% chance of working, never saw an issue * DDR5-6000 - 90-95% chance of working. It works for most people, but I've seen the occasional case where it causes crashing, stuttering, freezing, etc. In these rare cases, slowing it to 5600-5800 fixed it. * DDR5-6400 - 10-25% chance of working. For most people it doesn't work, occasionally someone gets lucky.
Now the good thing with faster RAM is you can slow it down. You can slow down 6400CL32 @ 1.4V to: * 6200 CL31 @ 1.4V * 6000 CL30 @ 1.4V * 5800 CL29 @ 1.4V * 5600 CL28 @ 1.4V
Lowering the CAS Latency (CL) gives you back a good chunk of the lost performance.
If you have ChatGPT Plus, it's great for calculating the other latencies using o1-Preview - you can see the table in the end: https://chatgpt.com/share/670df260-7354-800e-a781-2da4972d4477
Once you figure out the ideal speed, you can tighten the tRCD, tRP, and tRAS in the BIOS for max performance.
Yestum@reddit (OP)
Wow I didn’t even checked if the cpu could handle those speeds, I’m gonna be trying what you recommend and lower it to 5600 Mt and maybe try to set it at 5800 Mt while checking the stability with a ram tester
DZCreeper@reddit
The vast majority of AM5 CPU's can handle DDR5 6000 if you are only using 2 sticks. AMD even uses that speed in most of their marketing material.
They only officially support lower speeds to give themselves some margin for error. For example, Zen 4 and Zen 5 have a physically identical memory controller but the support went from 5200 to 5600. That is a result of their increased confidence in their own product.
Yestum@reddit (OP)
Yeah I’m gonna try to push it to 6000 and check the stability of it, although I’m a bit worried about those issues that the 7800x3d had where the cpu would burn due to the ram speed and the expo mode with some MB. Is that still an issue to worry about when doing this?
DZCreeper@reddit
That was due to motherboard vendors allowing excessive SOC voltage. Newer BIOS versions have a 1.3 limit enforced, if your motherboard was purchased in the last 12 months it should be safe.
Also, you can manually adjust the SOC voltage. Most CPU's only need 1.2-1.25 to hit 3000MHz UCLK, I have even some run stable at 1.15 SOC.
Yestum@reddit (OP)
Ahh, that makes more sense tbh, I was a bit worried about that haha. Yeah my motherboard is like a month old maybe less since I bought it so I’d guess it shouldn’t have any issues. Thanks for the help! I’ll definitely try to push it to 6000 Mt as long as it’s stable, I’m just hoping I won’t have any further problems with that ram kit.
DZCreeper@reddit
It will work just fine. XMP and EXPO largely have the same functionality, EXPO just sets some secondary timings on AMD systems.
However not all AM5 CPU's can run the 3200MHz UCLK needed to make DDR5 6400 perform optimally. For optimal results I recommend setting your kit to DDR5 6000 CL30, UCLK to 3000MHz, FCLK to 2000MHz, and manually tuning the timings.
https://www.youtube.com/watch?v=dlYxmRcdLVw
Yestum@reddit (OP)
Yeah I’ll definitely try that, I don’t think the xmp by itself will give me the best stability or performance so most likely that I will be tuning it manually, also thanks for the video!