DIMM Slot/s No Longer XMP

rebirth

rebirth

rebirth

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31 Mar 2010
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106
Hi intelligent people who hopefully can explain why this may occur.

I have been running four memory modules for over one and half years without problems at their rated 3600mhz speed. The system had been rock solid. The other day I switched out a GTX 1080 for a 3080Ti, then after a few days of greatness I realised my bios predated the Resizable BAR feature, so I updated the bios. The first problem I noticed was a laggy bios UI, then after setting things up (in bios) Windows then tried to repair itself. It booted, but I was getting lockups. I tested the system and it was corrupt and wouldn't accept a repair. I then went ahead and tested the memory in Memtestx86 from pen drive. It detected errors, so I tested the sticks individually (think I used B2) and they all passed (in XMP profile). I then started to test the DIMM slots only to discover both A1 and B1 won't run at XMP (they would just revert to JEDEC 2666 speed with 1.35v on the dram), whilst A2 and B2 will.

I then reverted to the bios I was using but the problem remained. I settled with XMP using two modules in A2 and B2 and everything was solid, but of course I wasn't happy. So, after a day or so of slightly unhappy gaming I tried another bios (one down but still with Resizable Bar features) and it flashed OK and the UI is as snappy as the old bios I was using. Same memory problem. I then did the obvious thing and changed the graphics card to something very weak, but again, the memory problem was still there.

Using one module in A1 I was able to mimick 3200mhz C16 manually and the system booted and held the speed (3600mhz c18 didn't). This is where I stopped because it's baffling me, since 3600 mhz c18 and 3200mhz c16 isn't all that different on balance.

* I also thoroughly cleared cmos throughout testing.

My specs:
R7 3700x - I don't OC it (no point) but I did use a tweaked PBO, which is currently disabled.
32gb Corsair Vengeance 3600mhz c18 (4x8 same brand and matching chips - worked for a long time together, but they're still two sets of 2xdual channels).
3080Ti (Gaming OC)
Gigabyte Aorus x570 Elite (rev 1.0) currently running F34 bios.
850w PSU
etc etc

The only things I can think of is the IMC or a fault developed on the board. The board has some warranty left, but the CPU doesn't. 32gb is needed for development work.
 
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mickyflinn said:
Can you get all 4 sticks running at stock settings ?
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That's another thing I found very odd. I haven't tried since I fixed the OS, but I could get them to work at 3600mhz, and they even passed a lengthy memtest (1.5-2 hours). They failed in Prime95 within 10 minutes straight after, and then failed in memtest straight after that within about 10 minutes. Intermittent problem, apparently, but the fact that they won't run at that speed individually on those slots only makes me not want to try anything else until I get a better idea. I imagine they'd all probably work at 3200mhz c16, but I feel there's a fault somewhere on those slots (A1/B1) and don't want to make it worse. I tried that after I reverted to my original bios.

I also tried 1.35-1.36-1.37v on dram in following 4x8 tests, and even manually tuned the timings to match XMP, but it made no difference (still unstable).
 
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rebirth said:
That's another thing I found very odd. I haven't tried since I fixed the OS, but I could get them to work at 3600mhz, and they even passed a lengthy memtest (1.5-2 hours). They failed in Prime95 within 10 minutes straight after, and then failed in memtest straight after that within about 10 minutes. Intimmitent problem, apparently, but the fact that they won't run at that speed individually on those slots only makes me not want to try anything else until I get a better idea. I imagine they'd all probably work at 3200mhz c16, but I feel there's a fault somewhere on those slots (A1/B1) and don't want to make it worse. I tried that after I reverted to my original bios.

I also tried 1.35-1.36-1.37v on dram in following 4x8 tests, and even manually tuned the timings to match XMP, but it made no difference (still unstable).
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Probablly a fault with the motherboard .

Any chance you knocked the cpu slot when changing gpu's ? Mite be worth checking the cpu for bent pins.
 
mickyflinn said:
Probablly a fault with the motherboard .

Any chance you knocked the cpu slot when changing gpu's ? Mite be worth checking the cpu for bent pins.
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I'm usually careful, but I am using a Noctua D15. I dread a full strip down, but I'll dig out some paste later and remove the cooler and check. Do you think it's worth removing the motherboard in case I find nothing wrong with the CPU? I did inspect around the DIMMs but couldn't see any damage.
 
rebirth said:
I'm usually careful, but I am using a Noctua D15. I dread a full strip down, but I'll dig out some paste later and remove the cooler and check. Do you think it's worth removing the motherboard in case I find nothing wrong with the CPU? I did inspect around the DIMMs but couldn't see any damage.
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Could do but your going to have to send the motherboard or cpu back to get tested depending what you find .
 
I took off the heatsink, and cleaned and inspected the CPU. It's immaculate and no signs of any damage at or around the socket. It dropped back in without any problems. Sadly, it still won't accept XMP on A1. The PC just shuts off (telling sign, since it only soft restarts on accepted values), and starts, then seems to be trying to set the rating (going by the fan speeds), but just ends up at 2666mhz.

*
I have been searching around some more (trying to get the correct search phrase) and found that some of these AMD boards won't accept XMP on these slots and moving their two sticks to A2 and B2 was the solution for them: https://www.reddit.com/r/ASRock/comments/rjf5df/asrock_b450m_pro4f_xmp_not_working_corsair_3200mhz/

When I had only two sticks when building the PC, I did read the manual and followed their suggestion to use A2 and B2, but I just thought it was a thermal thing and forgot about it (I came from several Intel builds, so AMD was new to me). Going by the seemingly peculiar issues I have been having is it possible that my particular board won't accept these slots in two dimm mode at high frequencies unless all four are populated?

I can't find any info about this for my board, and then there's the issue where I could get it to hold 3200mhz on A1 (only went into bios after to see, didn't want to risk corruption).

If I could confirm this I'll stick each stick through a few 2-4 hour memtest cycles and hope one stick eventually fails. I think the two I've been using are fine (been a couple of days of heavy use). Swapping out the memory to 2x16gb would be less painful.

*
Dug out the manual but all it says is: "For optimum performance, when enabling Dual Channel mode with two memory modules, we recommend that you install them in the DDR4_A2 and DDR4_B2 sockets".

It doesn't say why, though, and the config table shows the a1/b1 configuration, but no mention of memory speeds or any limitations.
 
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OK, further searching reveals that a2 and b2 act as terminators on these boards, which help with impedance, so I guess it's a2/b2 and only use the other two for all dimms. I'm going with it unless I find out anything more. I must have a faulty stick or just some degradation (fingers crossed).
 
Not saying you're wrong with any of your troubleshooting / conclusions, but I just wanted to state this anyhow.

The change in graphics card just prior to all this, it might be worth keeping in mind that the 3080 Ti has a TDP that is double the 1080. I don't know if that realistically means double the power consumption, but I can say that your case (and everything in it) will have a lot more heat to deal with and that extra heat can make stable overclocks, not stable anymore.

BIOS updates can also have a big impact on stability and an updated BIOS is not always more stable than an old BIOS. It is rare that a newer BIOS is a downgrade, but when a BIOS is adding features (and X570 has been out a long time now), that can be more likely to change things negatively.

Running 4 sticks at 3600 was often regarded as near the edge of what Zen 2 is capable of, many Zen 2 users had to drop down, so is it possible you had other settings that you used to make it stable, which have been lost in the CMOS reset?

Having to tweak the settings instead of just XMPing, is very common for AMD systems.
 
I am thinking that it's a combination of those things. I do recall running the sticks at XMP for a while after I got them, but I tuned them to c16 @ 1.37v and ran that for over a year. I was using F21 bios and stuck with it. The new card ran for a couple of days, but I cleared cmos before I tried F35 and ran the XMP for a while without issues (maybe it would have eventually crept up). After F35 I knew something was wrong when I was in bios. Back to F21 didn't fix it but the UI was back to normal. With two sticks I settled for F34, which seems to work well whilst offering the features I updated for. I think I was thrown off by the daisy chain so was looking for other issues. I imagine you're right about the card basically changing the system, so I'll sleep on it and get tweaking and testing tomorrow. I've ran extensive tests on the other kit and they're not throwing errors as a pair. I guess the new card won't let them run 4x XMP anymore without help, but i'll target the XMP timings and reinvestigate some of the power offsets, now that I've ruled out everything else (CPU paste was a little crusty, so worth changing).
 
Finally got all four working at 3600mhz, but stuck with c18. Disabled gear down mode and set command rate to 2t. Soc is at 1.1v and dram at 1.37v (so tried to use 1.36v). XMP plain doesn't work now on four so I set the primary timings and RC (left rest on auto). Simpler setup to the 3600mhz c16 I had. Still, it is quite cheap 2 stick ram sets working as four.

The laggy bios is down to disabling CSM on these boards, which is required for Resizable Bar. ctrl-alt-f6 will change the ui resolution which miraculously stops the UI lag (it was only mild but noticable).

Hopefully it doesn't blow up for at least a year.
 
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rebirth said:
Finally got all four working at 3600mhz, but stuck with c18. Disabled gear down mode and set command rate to 2t. Soc is at 1.1v and dram at 1.37v (so tried to use 1.36v). XMP plain doesn't work now on four so I set the primary timings and RC (left rest on auto). Simpler setup to the 3600mhz c16 I had. Still, it is quite cheap 2 stick ram sets working as four.

The laggy bios is down to disabling CSM on these boards, which is required for Resizable Bar. ctrl-alt-f6 will change the ui resolution which miraculously stops the UI lag (it was only mild but noticable).

Hopefully it doesn't blow up for at least a year.
Click to expand...

Glad you get some stability .

Do you think its a bios issiue with xmp ?
 
mickyflinn said:
Glad you get some stability .

Do you think its a bios issiue with xmp ?
Click to expand...
It could be, because I could run them all at XMP on the F21 bios and even got to c16 using the same power I'm using now, but with a lot of adjustments elsewhere (I don't think I could do it now, and don't want to push into higher volts). I also think my CPU has been left behind in a lot of the updates since the 5000s. Using f34 I can get the ram stable in memtest at 1.36v, but not in prime (blend/memory stress). The little extra is probably keeping the IMC happy, and I'd say they're stable now. The other possiible alternative is PSU, but I'm not having problems when the card is under heavy use.
 
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rebirth said:
It could be, because I could run them all at XMP on the F21 bios and even got to c16 using the same power I'm using now, but with a lot of adjustments elsewhere (I don't think I could do it now, and don't want to push into higher volts). I also think my CPU has been left behind in a lot of the updates since the 5000s. Using f34 I can get the ram stable in memtest at 1.36v, but not in prime (blend/memory stress). The little extra is probably keeping the IMC happy, and I'd say they're stable now. The other possiible alternative is PSU, but I'm not having problems when the card is under heavy use.
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Would agree.

Can't see it being the psu , mite he tempted to fire an email to Gigabyte but if the memory is not on there qvl list wouldn't expect much. Possibility they get you to return the board but the your stuck until.

You just going to stick with it ?
 
mickyflinn said:
Would agree.

Can't see it being the psu , mite he tempted to fire an email to Gigabyte but if the memory is not on there qvl list wouldn't expect much. Possibility they get you to return the board but the your stuck until.

You just going to stick with it ?
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If it holds, yes. But I don't think I will be upgrading the CPU. Using 2 sticks of RAM it works fine in XMP (the sticks as pairs are on their QVL), so I doubt they'd regard this as a fault considering they're not really meant to work as four. I think we're on our own in these cases, but I could let them know. I will probably go back to Intel at some point. I only went Ryzen because they were considerbly cheaper than Intel's rivel at the time. AMD became less appealing after they raised the prices on the 5000s.
 
MasterBaker said:
Maybe something similar that Jayz2cents found out about the problem with the 3080Ti and only with the 3080Ti and updating your motherboard bios?
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when i got my 6600xt last month it wouldn't work with my monitor and i had to get a new one.
it worked with ever screen in the house but not my AOC 1440p monitor.
 
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