Background:

 

About 6 months ago or so my main unraid server started having issues. It was determined that a RAM slot on the mobo had gone bad and given its age I ended up having to replace the CPU, Mobo, & RAM.

 

I initially picked out a i7-12700k, an MSI Mag Z790 Tomahawk WIFI board, and 2 kits of corsair DDR5 RAM, seemed simple enough. Well the RAM came in and each kit had 1 stick with errors, i contacted corsair, blah blah blah, they tell me mixing and matching separate kits is not recommended on DDR5. Ok news to me, whatever I'll RMA the kits, resell them on ebay and buy a single kit that meets my needs.

 

So I bought a 4 DIMM corsair kit (CMH64GX5M4B5600C36). I checked it real quick on PC Part Picker for compatibility issues because i was in the badlands south dakota at the time and didn't have the time or internet service to really dig into finding "the best" replacement kit, i just needed something on order so it would be there when I got back. It didn't flag any issues other than the CPU not coming with a cooler which I knew.

 

 

What's happening now:

 

Well the new kit has also been nothing but trouble. The server runs fine and passes memtest left running over night but I can't reboot it without it starting to a black screen and the BIOS not POSTing. If you shuffle the RAM around it will boot again and run fine for months on end until I have to reboot it again. This is without XMP enabled.

 

But after two failed attempts to get a working set of DDR5 for this build I'm nervous to pull the trigger on anything else without extra eyes on my decisions.

 

So a general question for those more in the know on recent hardware developments than me. What is the deal with the seemingly random incompatibility claims? Intel ARK says my 12th gen CPU is compatible with DDR5 up to 4800MT/s. But if you look at corsairs site for the kit I bought they claim it's only compatible with 13th gen Intel CPUs or newer?

 

I'm looking at a G.Skill kit (F5-5600J3036D32GX2-RM5RK) from MSI's list and its the same thing, my mobo is on the QLV list but ONLY for 13th & 14th Gen CPUs.

 

But if you go look at MSI's QLV for my mobo, it lists that exact G.Skill Kit (F5-5600J3036D32GX2-RM5RK) as compatible with a 12th gen K series.

 

So What's the deal? Why do RAM makers seem to be much more limited in their compatibility claims than the mobo maker and intel are?

 

Then I've got kingston over here (KF556C40BBAK2-64 another kit off MSI's QLV list for 12 then CPUs) who makes absolutely zero compatibility limiting claims either on the product page or datasheet for that kit. So who do I trust? Am I just going to have to go kit by kit and check my Mobo/CPU combo compatibility against every single kit i look at?

 

I emailed G.Skill about the discrepancy between MSI's QLV and theirs and am waiting for a response back.

 

If I had known going 12th gen to save a bit of $$ was going to cause me such headaches with RAM compatibility i would have just bought a 13th gen outright. But I'm stuck with the 12th now so I'm trying to make it work.

Edited October 14, 20241 yr by weirdcrap

14 minutes ago, weirdcrap said:

but I can't reboot it without it booting to a black screen and not posting.

This likely because "fast boot" was enable in BIOS, just disable will be fine.

Just now, Vr2Io said:

This likely because "fast boot" was enable in BIOS, just disable will be fine.

I don't think it is but I'll double check. That's a good suggestion. Why would fast boot cause that behavior and why would shuffling around the RAM seem to "fix" it?

Just now, weirdcrap said:

Why would fast boot cause that behavior and why would shuffling around the RAM seem to "fix" it?

Fast Boot does not "look for changes" but just applies the last known hardware config. If something has changed, it fails to initialise the new hardware or gets lost whilst trying to setup the now missing one.

Shuffling around may help because the Mobo should then realize the change in serial numbers of the RAMs and disable fast boot then for the next try.

 

6 minutes ago, MAM59 said:

Fast Boot does not "look for changes" but just applies the last known hardware config. If something has changed, it fails to initialise the new hardware or gets lost whilst trying to setup the now missing one.

Shuffling around may help because the Mobo should then realize the change in serial numbers of the RAMs and disable fast boot then for the next try.

 

Ok I'll have to check and report back. It will take me a bit to get over there.

12 minutes ago, weirdcrap said:

I don't think it is but I'll double check. That's a good suggestion. Why would fast boot cause that behavior and why would shuffling around the RAM seem to "fix" it?

More precisely, the symptom are if you enable fast-boot, then reboot Unraid will got black screen, if you enter BIOS setting then quit then Unraid will boot normally. This already well address a problem.

Edited October 14, 20241 yr by Vr2Io

4 minutes ago, Vr2Io said:

More precisely, the symptom are if you enable fast-boot, then booting Unraid will got to black screen, if you enter BIOS setting then quit then Unraid will boot normally. This already well address a problem.

So you're saying if I had fast boot enabled the BIOS would post but then it goes to black screen rather than to the unraid boot? If so it's not doing that, the BIOS doesn't even post. You can't get into the BIOS settings or anything. You have to shuffle the RAM to get it so you can even mess with the BIOS.

 

But I'll check fast boot when I get over there and report back.

Edited October 14, 20241 yr by weirdcrap

your symptoms look more like "bad cpu" or "bad motherboard" to me but like "bad ram".

And if memtest runs fine for a night or so, the RAM maybe really not the problem here.

 

Overclocking? if yes, TURN IT OFF!

Undervolting? TURN IT OFF!

 

(I dont use Intel CPUs for over a decade or even longer already, I cannot help with details )

 

13 minutes ago, MAM59 said:

your symptoms look more like "bad cpu" or "bad motherboard" to me but like "bad ram".

And if memtest runs fine for a night or so, the RAM maybe really not the problem here.

 

Overclocking? if yes, TURN IT OFF!

Undervolting? TURN IT OFF!

 

(I dont use Intel CPUs for over a decade or even longer already, I cannot help with details )

 

No overclocking/undervolting. The K Series CPU is just what came in the mobo cpu bundle I bought, I didn't buy it with the intention of overclocking anything. everything is bone stock for maximum reliability.

 

I assumed it was RAM again as the corsair kit i bought passes memtest but is not listed on the QLV list from MSI so i just assumed it was some DDR5 compatibility nonsense. I figured if I get a new RAM kit that matches up across the board (everyone says compatible with everyone else) and it's still doing this then I can look at other things. It was also doing this with the last kit which was failing memtests.

I've got no symptoms besides the failure to boot without messing with the RAM. There are no errors in UnRAID when it's running.

 

What makes you say CPU/Mobo?

Edited October 14, 20241 yr by weirdcrap

1 hour ago, weirdcrap said:

What makes you say CPU/Mobo?

Even with failed or no RAM at all, CPU should reset and enter BIOS at least.

 

If all stays blank there is a serious problem with either comes from the CPU itself, or the chipset (that does not switch in the BIOS ROM at the right time).

 

Some MoBos have LEDs that signal which part of the reset process ist currently underway, dunno if yours too offers such diagnostic features. Even a BEEP can be helpful.

 

Next Time instead of shuffling parts around you should try to clear cmos and see if it comes up then.

 

 

28 minutes ago, MAM59 said:

Even with failed or no RAM at all, CPU should reset and enter BIOS at least.

 

If all stays blank there is a serious problem with either comes from the CPU itself, or the chipset (that does not switch in the BIOS ROM at the right time).

 

Some MoBos have LEDs that signal which part of the reset process ist currently underway, dunno if yours too offers such diagnostic features. Even a BEEP can be helpful.

 

Next Time instead of shuffling parts around you should try to clear cmos and see if it comes up then.

 

 

@Vr2Iohad it right. Apparently I had left fast boot on by mistake. I swear it was off so I never bothered to recheck the boot settings. I've rebooted 3 times back to back and it came right back each time.

1 hour ago, weirdcrap said:

@Vr2Iohad it right. Apparently I had left fast boot on by mistake. I swear it was off so I never bothered to recheck the boot settings. I've rebooted 3 times back to back and it came right back each time.

Thanks your feedback, I fully understand why you would point to memory problem, because swap modules seems fix it.

 

I also face fast-boot issue and have troubleshoot, so I know what will misleading the cause.

Edited October 14, 20241 yr by Vr2Io