I have a dell Inspiron 540. A month ago it had windows 10 on it and started crashing. I replaced the hard drive reinstalled windows 10 same issue. I recently downgraded it to windows 7 the original os with the same problem. It seems to crash more often when WATCHING VIDEOS on my computer and also YouTube. I replaced the graphics card twice and am still getting the same issue. I ran a test on the ram slots seemed to check out ok. Any help WOULD be appreciated memory testers are good but not 100%.
it could still be memory related.
if you have multiple sticks, just try running with one and seeing if the problem repeats.

it still leaves a question mark over the mobo and CPU.

you can probably rule of malware and the like since you have done a couple of reinstalls across multiple OS's.

what is the crash?  do you get an error message, a BSOD?In windows 10 the BSOD said fltmgr.sys error. I got a different one in windows 7 if it pops up again I'll post it.You running ESET >? ?No no ESET