Question RAM Speed issues on ASUS X870E ROG CROSSHAIR HERO

[pegabee]

Hi All

I've been running around like crazy trying to troubleshoot this issue but running out of options.

TLDR: I can't get my MB (ASUS X870E ROG CROSSHAIR HERO) to post with 4x stick of 8000MT DDR5 ram (G.SKILL Trident Z5 Royal Neo Series (AMD Expo) DDR5 RAM 32GB (2x16GB) 8000MT/s CL38-48-48-128 1.45V Desktop Computer Memory UDIMM - Silver). Interestingly if i remove 2x sticks and just run dual channel ram with the exact same kit I can post no problem with Expo enabled and 32gb running at 8000MT

Before the obvious: yes I'm running the latest version of BIOS, updated today - was running a previous last non-Beta version before.

I can post with 64gb RAM if:

1. I leave everything at auto , but then the ram is only running at 3200
2. was painfully able to somehow get the system to post if i left everything at auto (no expo) and manually set the ram speed to 7000. Loading into windows took a good 2 mins this way
   1. I can't replicate this with any 8000 manual setting.

AI CPU tweaking is currently turned off

Other system specs:

• CPU: AMD 9800X3D
• 3x M.2 SSDs
• 3090 GTX
• 1300 PSU

enabling any of the EXPO profiles seem to completely stop the posting process with all 4x ram sticks populated, with dual it's no problem

I've actually gone ahead and purchase 2 more sets, so now i have 8x ram modules, tried to swap them around in the slots, nothing seem to have made any impact. Even received a replacement MB but I still couldn't post at full speed with all ram modules.

Running out of ideas what else I could do besides manually setting everything, which I am honestly not really experienced with, so any tips would help... already considering downgrading to lower speed & higher capacity modules and just run dual channel if I can resolve this.

Thanks in advance for any tips !

 

[thestryker]

Running 2DPC DDR5 at high speed is just not going to happen on any platform, but especially AMD. The frequencies are simply too high for 2DPC so if you need more than 32GB DRAM at high speed you need to be looking at higher capacity modules to run 1DPC.

 

[PiersPlowman]

Rated memory speeds for the 9800x3D:

2x1RDDR5-5600
2x2RDDR5-5600
4x1RDDR5-3600
4x2RDDR5-3600

You cannot just punch in a number and expect it to work .

 

[Misgar]

2x1RDDR5-5600
2x2RDDR5-5600
4x1RDDR5-3600
4x2RDDR5-3600

Just in case the above isn't immediately clear to a neophyte:

The quoted speeds 5600 and 3600MT/s are those guaranteed to work by AMD for your CPU. Higher XMP/EXPO speeds may be attainable, but they're not guaranteed by AMD. It's Silicon lottery time.

For systems using 2 DIMMs:

2x1RDDR5-5600 refers to two DIMMs of "single rank" (1R) construction running at 5600MT/s
2x2RDDR5-5600 means two DIMM with "dual rank" (2R) construction also at 5600MT/s
https://www.technewstoday.com/single-rank-vs-dual-rank-ram/

Then we get to 4 DIMMs which are harder to drive than 2 DIMMs, especially on Ryzens:

4x1RDDR5-3600 is four DIMMs, single rank (1R) with speed reduced to 3600MT/s for stability
4x2RDDR5-3600 as above, but dual rank (2R) at 3600MT/s

I've seen instances where 4 dual rank DIMMs supposedly need even slower speeds than 4 single rank builds, e.g. 3200MT/s.

Enough of the theory. I must admit I burst out laughing when I saw 4 DIMMs clocked at DDR5-8000 on a Ryzen. I'm running my old 7950X at DDR5-4800 (2x32GB), because faster RAM was much more expensive back in 2022.

I think you're on to a winner if you can run 2 DIMMs at 8000MT/s, but I doubt if you'll reach 7,000 with four DIMMs. You might have to settle for 6000 or even lower with 4 DIMMs.

I leave everything at auto , but then the ram is only running at 3200

Are you sure it's running at 3200MT/s? The JEDEC default for DDR5 prorammed into the SPD chip is typically somewhat higher, e.g. 4800MT/s. It's possible the BIOS has spotted 4 DIMMs and reduced the speed to safe levels for stability.

I'm running my 2x32GB Kingston Fury at the 4800MT/s SPD JEDEC timings and XMP/EXPO switched off. Check with HWMonitor, Aida64 or similar sofware to see if you really are running as slow as 3200MT/s with EXPO switched off.

Try installing 4 DIMMs and set the memory to stock JEDEC (non overclocked) speed, e.g. 4800MT/s. See if the computer boots into Windows. You might have to start at 3600MT/s.

If successful, manually select a slightly faster XMP/EXPO setting, e.g. 5200MT/s. Try booting again.

Continue, increasing the overclock in 200MT/s increments, e.g. 5400, 5600, 5800, 6000, 6200, etc.

If you're impatient, increase in 400MT/s steps from 5200, i.e. 5600, 6000, 6400, etc.

You'll reach a point where the system crashes. Reduce the overclock by 200MT/s and boot the computer from a USB memory stick containing MemTest86. Run a complete scan. With 64GB this will take a long time (several hours) but it's an important check for stability.
https://www.memtest86.com/

If MemTest generates even one error, your system isn't stable. Reduce the XMP/EXPO setting by another 200MT/s. Run MemTest again (full run).

I've actually gone ahead and purchase 2 more sets, so now i have 8x ram modules,

Not a good idea. The pundits will advise you to buy a single kit of 4 matched DIMMs, not two (or in your case four) kits containing 2 DIMMs each. You're fitting unmatched pairs which can cause problems.

Before a manufacturer assembles a batch of DIMMs, they test thousands of individual memory chips and sort them into bins according to speed. Slower chips will end up in one bin. Faster chips in a second bin. Super fast chips in a third bin and so on.

They then take memory chips out of these bins and build slow/medium/fast DIMMs. The slow chips that cannot be overclocked end up on cheaper DIMMs. The faster binned chips end up on more expensive DIMMs.

Next, they test each completed DIMM and group virtually identical DIMMs into sets, e.g. sets of 2 matched DIMMs, sets of 4 matched DIMMs, etc. Of course the DIMMs are not truly "intentical" but the timings are closely matched.

Unfortunately, when you buy two sets of DIMMs from your local supplier, even if they have exactly the same part number, the memory chips may come from different bins and have subtly different timings.

With some DIMMs (Corsair Vengeance?) there exists the possibility you might get Hynix memory chips on one pair of DIMMs and Samsung memory chips on another pair. Mixing memory chips from different manufacturers makes fast overclocks even more difficult.

Two unmatched pairs of DIMMs might work at the JEDEC default speed of roughly 4800MT/s, better still at 3600MT/s, but you're asking for trouble as you head up towards the stratospheric speed of 8000MT/s with four DIMMs on a Ryzen.

Forget 8000MT/s with 4 DIMMs. Test carefully and accept whatever the Silicon lottery gives you. I'd consider buying 6400MT/s DIMMs for my 7950X rig if I was building it now, but programs like Adobe Premiere don't benefit much from faster RAM on Ryzens, unlike Intel CPUs.