Question Unstable system only when both RAM modules are installed - what is at fault?

[Rogach]

My system becomes unstable if I install both RAM modules (I can reliably get errors using Prime95 large-memory and blend modes, and get other random crashes from random software), but when I try one module at a time errors go away (tried that for both modules). What could be the cause of the issue? Is it faulty motherboard or the fauly RAM modules?

I ran memtest86 on these RAM modules, got zero errors. Tried changing memory frequency/timings - no effect, errors are present with two modules on all frequencies (even really low ones) and on all timings (even if I set them to maximum).

System info:
RAM: 2x Patriot Memory VIPER STEEL PVS464G360C8K 32GB, from the same kit
Motherboard: ASUS TUF GAMING B550-PLUS
CPU: AMD Ryzen 9 3950x

 

[razel]

Have you tried testing one stick at a time for both sticks in your kit.

 

[Rogach]

Yes, that's what I tried - errors go away when only one stick at a time is installed (I updated the post with better wording).

 

[razel]

How about putting just one stick in that 2nd slot when you put in both and test that 2nd slot only? Thinking maybe an issue with the 2nd slot only.

 

[Rogach]

Tried putting in each stick into each slot, got no immediate errors in any combination.

However in extended tests one of the sticks gives a single error after a long time - about 30-60 minutes into the test. Should I assume the module is faulty?

 

[fralexandr]

Yes, if memtest returns any errors there is a problem with that stick of RAM or that slot.
Are you testing at 3600? Have you tried with xmp disabled at the default 2133 or 2400?
I'm guessing that one stick probably has trouble reaching 3600.

You might want to return/exchange or warranty it. If you need to use the warranty, hopefully patriot lets you return just 1 stick.

 

[Rogach]

No, I was testing at default 2666, no XMP (separate modules or both at the same time). That was not memtest, that was Prime95, but I think the conclusion is the same.

I verified that the modules are the culprit - took them to the friend's computer, installed them and got just the same errors. Friend's modules do not give any errors when installed into my computer. He has 16GB modules while I have 32GB, but I don't think that is relevant.

I think I will try returning both modules, because I'm not sure that only one module is broken - the error I was getting on that one module took a long time to reproduce, while errors with two modules were almost instant.

 

[bryanl]

Generally the problem is crappy or overclocked memory. Patriot rates it 3600, 18-20-20-40, 1.35V, only there's no such thing in DDR4, which goes up to only 3200, 22-22-22-32 and operates at 1.20V (absolute max. is 1.50V), according to the chip manufacturers. Memory tests run on PCs aren't nearly as thorough as those done by the RAM chip manufacturers