Question My PC won't detect my GPU anymore, GPU works on other PCs, other GPUs work on my PC

[bigbig123]

I've got an old PC which I use for surfing the web, and it has an old 8600GT graphics card.
In the past PC wasn't able to recognize it a few times, but I fixed that by reseating the graphics card and cleaning up the dust.

However, since yesterday my PC won't boot at all, and I only get the beeping noise.
I removed the GPU, cleaned the dust, reseted the GPU. No dice.
Tried a friend's GPU on my PC, it works great.
Tried my 8600GT on my friend's PC and it works without any problems.

It appears that issue appears only on my PC. What gives?

Buying a new GPU isn't probably worth it, since the entire PC is worth about 50$ tops, and used GPU is about 20-30$.
Is there any way to fix this?

 

[bigbig123]

bump

 

[lynx1021]

What was your friends GPU you tried? Maybe there is something loose and made contact when you tried friend's GPU. Try reseating memory and all power connections, one of my pc's would boot the other day and I had to reseat the connector that goes to my power switch!