computer help please

general technical question if anyone can help. A few years ago i bought a used / referb dell precision 490. its a tank, i could prob save money from the pfit and just work out lifting this thing instead. anyway the other day i was just playing on the net nothing major and it just shuts off. i reboot it and it works fine. then it shuts off again. it reboots with a thermal error. i take the case apart and blow it out with some air. it was not bad. i reboot and same error. i take the cpu off clean the old thermal paste off and reapply and i take the cmos battery out to reset it and replace and it boots fine. i have 2 monitors and start playing coh on one screen and watching youtube on the other. i do this for 2 hours no problem. then it just shuts off again and on reboot it says my memory something has changed. i reboot and install some cpu temp monitoring app and its going fine but will still randomly shut down. i was thinking that it may be faulty power supply unit. or the mainboard mayhap is faulty. i dont have an extra power supply and the computer uses a 750w a new one is just under a hundred but another referb computer is 400. what do you think is it the psu or mainboard. thanks.

"dell precision 490", that tells me nothing without its exact configuration

"pfit and just work out lifting this thing instead" the f**k you saying?

memory something ? most likely the word was configuration, which would mean you touched/removed the ram dimms moved them to another slot or something

what app? some are known to suck hard in reporting temperatures accurately and are in fact just bloatware

coh ? im asuming company of heroes, but which one? one is way more demanding then the other

dell uses f**ked up formfactors to begin with, finding a new motherboard basically means you can toss the whole thing and buy a new pc
if its the PSU, the same thing could apply depending on if they use a f**ked up formfactor here as well

basically, everything is in the details, which i cant find here

Dell precision 490 xeon dual core processor e5345@2.33
Processor bus 1333
4 ram sticks
DDR 2 667 4gb each
speedfan is the app
ya company of heroes 1 just saying i dont think it was an actual cooling issue unless is a power supply.
thats cool if no one knows whats wrong off the stats i stated i may just need to dump it and move on.
ive had it a few years and the problems suddenly developed all with in a short time span. it seams like psu or mb. i did nothing to the ram configuration and im sure that i did not bump them during the whole process.

Try a new cmos battery.
Some years ago, friend had a base unit doing all sorts of weird shit, eventually it progressed to a shut-down/reboot/shut-down loop. new battery cured it.

Considering the fact its ancient in computers term, ^ battery might work (unlikely though), or just toss the paperweight.

And don't replace one paperweight with another by buying a refurb.
More often then not they are refurb for a reason, a reason that might not instantly but soon make itself known, and your back at square 1.

For $400 you can get a new system, although it would be rather lowish spec and not that much of an improvement, up it to 600 and you can do SO MUCH more and build something that would completely destroy the paperweight you have now with 2 fingers up its nose.
Look here for some examples, pretty much all of them could run any game on at least 1080p high+ settings.

I think you forgot the link, but yeah for $400 you could build a new computer with a 3200g, 16GB RAM and an SSD.

https://pcpartpicker.com/guide/

or for $550 you could get something like https://pcpartpicker.com/list/JZnFFG

Huh yeah ...it seems ....weird
Anyways i was about to post pretty much the same thing
https://pcpartpicker.com/builds/#X=54974,65691

ok thanks for the help