Z420 Crashing Under Load

[ShovelMonkey]

Hello,

Long time listener, first time caller...sorry, I have a singular wit.

Anyways:

I'm fairly new to the world of used workstations, I have a Z420 that I've upgraded with multiple options.

It came with a 1650 v2 that I upgraded to a 2670 v2. Both of those CPU's seemed to run fairly stable. I nabbed a 2680 v2, this cpu crashed under load testing (prime95 / cinebench R23), I also nabbed a 2690 v2 same results. I thought perhaps I lost the ebay lottery so I returned the 2690 for another and still same results. As I said, the 2670 seemingly works fine.

I thought perhaps it was a power delivery issue as the 2690 is a higher tdp part, so I replaced the OEM psu with a known working fairly new 750w unit that I have. Still same results. I have also upgraded to the z440 cooler and temps are fantastic with all the cpu's idling in the high 20's. The 2670 never exceeds the mid 50's under load and the 2680 / 2690 crash in the mid 50's so I do not believe it to be a thermal issue. 

Am I looking at failing power delivery with the motherboard? This is the only thing I can think of at the moment.

[DGroves]

does the system only crash when doing testing/stressing the system? if so what are you using for the test? does it test the CPU and Ram at the same time? again if so have you tested just the ram? and just what ram (part number) are you using and how many modules?

the 2680 v2 is a 130 watt part the 2690 is a 150 watt part as i recall

[ShovelMonkey]

The system "generally" only crashes when stress testing. However, the 2680 v2 and 2690 v2 will crash with moderate loads placed on them under typical workloads for an aging system. I'm using it as a home server so this includes moving files, a jellyfin server, and a dedicated Valheim server.

Here is a link to the intel compare sheet for the three processers I've swapped in and out: https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=75275,75277,75279

I find it puzzling that the 2670 v2 is stable and the 2680 v2 is not as they are the same tdp (115w). I've had three different 2690 v2's that I've purchased off of ebay with the same results...which is crash crash and more crash. The 2690 v2 is a 130w part. 

I have ran memtest on the memory which is an 8 x 8gb configuration of 1600 mhz ecc ddr3, passed with flying colors. Not sure on the part number without ripping it appart (which I will be soon).

Stress tests I've used are prime95 and cinebench r23. I don't believe cinebench tests the memory, not sure about prime95.