Computer power problems

[Dethanu]

So i have this old LGA775 pc that i had in a old storage room for a while and the temps there can reach -10C. I made the rookie mistake of powering the PC in that area, the computer started but it shut down after a few minutes. Took it out of there and left it in a warm room for a few hours to heat up, then i tried to power it and the CPU fan and the case fan did only a rotation and that's it. No matter how many times i tried it only did that. So i got this new seasonic PSU , connected it, the PC boots but there is no signal to the monitor nor the keyboard. Checked the cable connections, and but the beeper on the MB. It starts but i get no beeps that something is wrong but still no video signal. Removed the memory and tried to start the PC, it boots but after a few seconds it shuts down with no beep. Put the memory back in and the PC runs for 3-6 seconds then shuts down. How can i fix this?