64 GB Corsair DDR5 6000 on TUF Gaming X870 Plus Wifi Motherboard

[mgilbert]

I have an Asus TUF Gaming X870 Plus Wi-Fi motherboard with the latest BIOS, running a 9900X CPU and 64 GB of Corsair DDR5 6000 (2 X 32 GB) CL30 RAM - Model CMH64GX5M2M6000Z30.  No matter the timings, it throws errors in tests 1 and 2 in MemTest86 if I try to actually run it at 6,000 MT/s.  EXPOI runs it at 1.4 volts.  The only way to get it stable is to run it at the default 4,800 MT/s, which has a CL of 40.

This actually makes very little to no difference in Cinebench runs, but I paid big bucks for this supposedly fast memory.  It's not on the QVL, but what was on that list was not available to me.  What am I doing wrong?

[Nate152]

Hello mgilbert

Do you have your memory installed in the A2-B2 slots (2nd & 4th slots from the cpu)?

[mgilbert]

Yes...  Since I get MemTest errors at 6,000 MT/s even with very loose timings, I'm thinking that the problem is strictly with the frequencies.  I'm going to experiment with the leaving the tight timings I paid for alone, and dropping the frequency.  I'll start at 5,600 MT/s.

[Nate152]

Ok sounds good.

Your memory part number shows 1.40v, so this is normal that it sets 1.40v when EXPO is enabled.

64GB 6000MT/s CL30 may need manual voltage tuning. It's not uncommon for high speed, high capacity, low latency memory kits to need manual voltage tuning.

[mgilbert]

Thanks!  I did some quick research into that.  Since the frequency, rather than the timings, seem to be the issue, what voltages would you tweak, and by what values?

And, do you have any idea what brand chipset is used in this memory?  I can't find that information online anywhere.

[mgilbert · Accepted solution]

To anyone interested, the solution to this issue came from Corsair support.  Despite only running at 6,000 MT/s, which sets the UCLK to 3,000 MHz, which is in spec, I had to drop the UCLK to 1/2.  And that solved the problem.

[mgilbert]

If anyone knows how to get UCLK stable at 1:1, please let me know.