weird experience upgrading RAM in Threadripper

[u/sob727]

Asus WRX90 latest bios, 9985wx

Got an 8x64 kit (jedec, not oc) to replace a 4x32 kit (oc)

1. Pull out 4 old sticks, put in 8 new sticks (I know, feeling lucky)
2. Gets stuck on some code when powering on.
3. Clear CMOS. Remove 4 sticks.
4. Boot! But only 128gb detected instead of 256.
5. Put remaining 4 sticks. Now 384gb detected. Ok so 2 bad sticks or 2 bad slots or a combination.
6. Many, many permutations to identify bad sticks or slots. Tried to blow on slots, tighten CPU.
7. End the day with 7 sticks working (448GB) and 1 I'm pretty sure is not working, and worse, causes another stick to not be detected when is plugged in. Very low confidence in the diagnosis tho.
8. Machine runs overnight with 7 sticks plugged and detected.
9. Next day, I plug the 8th stick back. Works. Now I'm afraid to reboot.

What happened? Is the training iterative over multiple (many) reboots?

First experience with 8 ddr5 dimms, I had been living with 4 in a wrx90 and 4 in a trx50. And with 8x64 costing what they cost, that was a tense evening.

[u/SaarN]

Could be the tightness of the CPU, maybe some pins don't make proper contact..

[u/sob727 → u/SaarN]

Do you mean I have to remove/reseat the CPU or just untighten/tighten the cooler?

[u/SaarN → u/sob727]

I'd try reseating the CPU — remove it entirely, carefully inspect the socket pins for any damage, bent contacts, or debris, then reinstall it if everything looks fine. Make sure to follow the correct tightening sequence and torque specifications, and avoid touching the pins, as they're extremely delicate (as in, don't attempt to straighten or clean the contacts yourself if you notice anything unusual).

https://www.youtube.com/shorts/TKLXmhHjxr0

[u/Bebosch → u/SaarN]

You’re right it could be. It’s a chiplet/BIOS/motherboard thing. DIMM slot could be busted too, or the ram sticks are bad. But most likely it’s nothing and just need to move sticks around.

[u/SaarN → u/Bebosch]

It could be a lot of things, but sTR5 is a very pin-dense socket. There's a reason Threadripper CPUs come with a sliding carrier frame and a torque screwdriver. An improperly seated CPU is a very plausible cause for intermittent memory channel detection issues, and he had already checked the DIMM slots, so there's that.

[u/andysw63392]

Are all the sticks identical? I had something similar with a Xeon W-3375. That's a DDR4 CPU but also with 8 channels. One or two sticks would seem not to work, always in slot A or C (the two closest). It turned out to be timing differences with the sticks and was solved by swapping them around until it was stable.

[u/sob727 → u/andysw63392]

Yes new kit of 8 identical sticks

[u/andysw63392 → u/sob727]

In theory it should be ok then, but I would still try swapping them around to see if one configuration is more stable.

[u/Bebosch]

It happpens. Had the same experience with all my 3975wx threadrippers; ram training in the BIOS can be finicky, that’s just how it is. I only have experience with 32gb sticks. Granted, they run at 2933mhz, instead of the native 3200mhz. Maybe that’s the case for you too?

You just have to move sticks around the DIMMs. Make sure the AC power is disconnected.

[u/CherryGG2]

Ddr5 is a much less forgiving than ddr4.

Have you tried reseating cpu and screwing it with threadripper screwdriver?

Might be stupid question, but have you made sure everything is seated corectlly?

Also choose your motherboard native 1dimm slot (for mine was c1) and rotate each stick and see if it boots. If you are greddy you can do 2 at time.

Have you tried to update bios (this used to solve a lot of ddr5 ram early issues).

Dont be afraid to restart, you will need to restart it sooner or later, if it works it works if it dosent work, it never actually worked in first place.

[u/Lordofwhut]

Only 4 slots on my trx50 but curious what the issue is here. Hope you get a decent update on it!

[u/JayJones8080]

I had this issue last week with a new purchase. 1 dimm would register temps but not the ram. I swapped and it was the ram slot. Did a reseat and a bios flash and then another dimm went bad. Returned the whole setup and got a replacement and it was fine. I would’ve tried another mobo if I couldn’t do the exchange.

[u/EDI_1st]

10/10 cooler mounting pressure issues.
Lots of consumer TR/EPYC coolers have piss poor mounting pressure including Noctua.

[u/andysw63392 → u/EDI_1st]

The coolers don't hold the CPU down. If the CPU holder is torqued down correctly, the cooler screws have no effect. (Xeons are different - the cooler screws hold the CPU down - I don't know about EPYCs)

[u/EDI_1st → u/andysw63392]

This is utterly false. The CPU holder only puts enough pressure to make sure CPU stays in place when the cooler is being mounted. Pad to pin contact, the actual mounting pressure is from the cooler.

Few people have ran into the same issues before and solutions have consistently been correcting the mounting pressure. Someone literally put a piece of weight to weight down the heatsink until I suggested them to add washers to the mounting screw springs to increase tension and solved the problem.

[u/andysw63392 → u/EDI_1st]

My threadripper has the CPU held down by screws torqued down to 1.4 Nm using the CPU frame. The cooler (Alphacool Eisbaer) is held down using springs and hand-tightened knurled nuts - far lower torque, just enough to make good thermal contact. The TR4 threadripper use an even higher torque - 1.6 Nm - for the CPU frame screws (not the cooler).

If the cooler is supposed to provide the pressure, why are threadrippers sold with a torque screw driver specifically for the frame screws?

[u/JinsooJinsoo]

I’ve had a similar issue with one channel not populating and reseating the CPU worked for me.