Question CPU artifacts?

[MarkerDaSharker]

So I bought a new PC, refurbished dell T5810. It worked fine up until a month in where i started getting weird screen artifacts, and over time they kept getting worse and worse to the point where a web browser would be half a black box and web videos would compress into 5/6ths the screen with a black bar on the other 1/5th for a second, and then it would refit to the entire screen and repeat over and over. I decided to look at ways of testing what was wrong, swapped out the GPU into an old rig and it worked fine there. I then decided to stress test this with prime95, and during the stress test almost every artifact went away and videos played normally. I thought this was due to clock speed considering it was a server CPU, but when i modified power settings to make it stay at 100% speed, it did still had the artifacts with low CPU usage. Has anyone experienced anything like this before and know how to fix it? One thing I didn't try yet was modifying the voltage in my bios, but looking at HW monitor it seems to always be in a normal range.

CPU: E5-2690 V3
MB: Dell T5810
GPU: 1080 TI

 

[MarkerDaSharker]

For anyone curious, as of right now I seemed to solve it by disabling intel speedstep in bios. I wish I could have a justification of why, but considering its refurbished my best guess is some sort of MOBO glitch or processor glitch in reading when it needs to speed up.