Question 3 computers all having the same problem, 2 Begin to work for no reason.


Nov 7, 2017
So I have 3 old crappy prebuilts that have had their fair share of workloads. Now the issue lies with them displaying nothing to any sort of monitor through any kind of cable.

Story time:
I keep 2 of these computers in my closet to test software and just to genuinely mess around with them, They are your cheap $200 prebuilts from HP and Gateway.
One day I discover that neither will display anything so I just put them back in the closet, I wasn't in the mood to troubleshoot.
About a couple of days later I remembered the problem and went for a few more boot ups (Hard drives+ALL fans working on both).
So I grab a third computer from my friend to test the ram to see if that's the problem, but to my horror, it just caused the same thing to happen to his PC.
Ram problem: I took the ram out of the Gateway computer and put it into my friends PC, it caused it to break as well, this ram never even TOUCHED the HP computer.
So now i'm thinking "well crap now I have 3 broken computers and one of them isn't even mine." So I go back to my 2 computers with the ram from the Gateway and discover that both the HP and gateway now magically work...
The problem is is that no matter what i've done to my friends PC I still cant get a display, its showing all the same signs (hard drive, fans, no signal) They all seemed fine but just wouldn't display anything.
I have: Applied new thermal paste in case of CPU overheating, tried booting without hard drive(nothing changed), attempted to power-cycle my friends PC, tried other cords+monitors, and tried booting without any ram on the MOBO, leaving the CMOS battery out, +plus many other things I read on these forums to fix it.
I have determined its either the PSU or the CPU,(as the MOBO beeps without ram, and the hard drive changes nothing) but what really stumps me is how the HP and Gateway made a full recovery like nothing happened after encountering the same problem. So doesn't this mean the my friends PC is okay?
I have no GPUs to test with the PC, they all use Integrated graphics.

If I have been too vague just call me out and Ill try to sum it up or even re-write this whole thing.

Ill give some vague specs here:

ram 4gb ddr3
CPU amd dual core something running at 1.4ghz
noname PSU
250gb HDD 7200rpm

ram 8gb ddr3
CPU amd quad core running at 2.2ghz
Has no PSU
1tb HDD 7200rpm

Freinds PC (its a Lenovo prebuilt)---
ram 4gb ddr3
CPU intel i5 3470 running at who knows I cant get a display
noname PSU
250gb HDD 7200rpm

(all single sticks of ram)

Short story: ram from gateway goes into Lenovo, Lenovo dies.
Ive read and tried almost everything online (even trying to push down on the heatsink for the cpu :p)

So does anybody have anymore Ideas before I throw out the Lenovo and pay my freind $300?