Gaming No output display on PC and powers off after 15 seconds

[luke_c]

A few days ago I decided on a whim to 'attempt' to take apart our very old and only desktop PC, no one uses this PC so I thought what the heck, just wanted to get a feel for how everything works. Now this PC is about 8-10 years old, so I am sure it was already quite close to it's death bed.

I removed all the components and motherboard from the case, gave it all a good clean (10 years of dust is not a nice sight.) and put it all back in without a hassle. When I booted the PC, my CRT monitor goes out of standby and says "No signal found !", whereas if I remove the GPU card nothing happens so I assume this means that it is detecting the GPU but something along the way is going wrong, terribly wrong...

Another thing is that I am getting zero beeps from the internal buzzer whatsoever, even when I removed both RAM sticks I still get no beeps, and I know it actually has a internal buzzer because I checked myself, it's a KC-1206 (Whether it is alive or not is a different story.) So at that point I could only really assume it was the CMOS battery...

I removed everything again, only putting back in the PSU, CPU, GPU, 1 RAM stick and the Heatsink fan/CPU fan and this time it powers off after about 15-20 seconds, with the same display problem to go along with it... Now my beliefs are that the PSU has started to die now, causing the power off problem (Or possibly overheating?) or/and the CMOS battery on the motherboard has gone which would also explain why the internal buzzer on the mobo isn't working... As for the reason I am getting no output display, I am clueless.

Yes, the monitor works, I have tried it on multiple other Computers. There is probably more stuff I meant to say but have forgotten but that's all I can remember for now, I don't plan on buying any new parts for this Computer as I will be attempting (

) to build my own computer within the next few months, so if it is dead, then so be it.

Just wondering if anybody has any suggestions/ideas as to what I could do from here to get this system working, albeit highly unlikely.
If needed I can provide pictures.

 

[luke_c]

Solved the power off problem, I swear I have done absolutely everything that is possible to do to try and get the display to work, I will try another monitor tommorow and try replacing the CMOS battery, if there is still no luck I am completely out of ideas and can only assume one of the parts is dead... Doesn't help that I can't locate that part as the internal buzzer seems to be borked, hopefully replacing the CMOS battery can fix that and then I would be able to find which part(s) are playing up...
EDIT: Took out the CMOS battery and waited a few minutes as this apparently clears it, popped it back in, same display problem but now with the added problem of the powering down again... Only few options I have left is to replace the CMOS battery, get a different VGA cable and try it on another different monitor, I may of fried something as I didn't ground myself when doing anything...

 

[sprogurt]

Did you reapply the thermal paste? If so what type?
What did you use to clean the mobo?
Try and replace the CMOS like you said.
Sorry, I know this sounds kinda patronising but make sure everything is reseated properly.

 

[luke_c]

Did you reapply the thermal paste? If so what type?
What did you use to clean the mobo?
Try and replace the CMOS like you said.
Sorry, I know this sounds kinda patronising but make sure everything is reseated properly.

Didn't reapply the thermal paste as I don't currently have any, I did lose a fair bit over my hands though when fiddling with the CPU and fan... Just bought some along with the CMOS battery though so when they come I will replace them.
I'v reseated the RAM sticks and the GPU 10 times each, as I heard that this can reduce oxidation build up which can cause them to not work correctly, still the problem persists...
As for cleaning the motherboard I would of used compressed air but alas as I am new to this whole thing did not have so I just used some tissues to get bits of dust off.

 

[sprogurt]

Didn't reapply the thermal paste as I don't currently have any, I did lose a fair bit over my hands though when fiddling with the CPU and fan... Just bought some along with the CMOS battery though so when they come I will replace them.
I'v reseated the RAM sticks and the GPU 10 times each, as I heard that this can reduce oxidation build up which can cause them to not work correctly, still the problem persists...
As for cleaning the motherboard I would of used compressed air but alas as I am new to this whole thing did not have so I just used some tissues to get bits of dust off.

What type? Just make sure the chip and the heatsink are spotless (don't scratch it off, my friend for cleaning a heatsink for me and took a knife to it >.

 

[luke_c]

Didn't reapply the thermal paste as I don't currently have any, I did lose a fair bit over my hands though when fiddling with the CPU and fan... Just bought some along with the CMOS battery though so when they come I will replace them.
I'v reseated the RAM sticks and the GPU 10 times each, as I heard that this can reduce oxidation build up which can cause them to not work correctly, still the problem persists...
As for cleaning the motherboard I would of used compressed air but alas as I am new to this whole thing did not have so I just used some tissues to get bits of dust off.

What type? Just make sure the chip and the heatsink are spotless (don't scratch it off, my friend for cleaning a heatsink for me and took a knife to it >.

 

[sprogurt]

Good, I use artic silver all the time now, the only time I didn't the damn machine overheated. It's quite effective, normally after the majority has gone you can apply the alcohol directly to the heatsink and leave it for a few minuites, it's alot easier than scrubbing at it. It will be effective on the chip too, you shouldn't need to directly apply te alcohol onto that.