Gateway lx6810 continuous beep, no boot

Fhydan

Honorable
Aug 9, 2013
2
0
10,510
HI,
I have a Gateway lx6810 from 2009. I've been on vacation last month so when I returned I found it rather dusty.
It wouldn't run anymore. It was giving no POST beeps, only the fans of the CPU and gpu would spin very fast.
I figured it must be the old psu so I got a corsair cx600 600watt new psu and plugged it in.
Now, when I turn it on I get one long constant beep.
I tried taking the memory modules out and tried every pair of (module, slot) . With all memory out and with all different settings of plugging the memorry, I get the same continuous beep.

Unfortunately for me, I can't find a manual for this motherboard (model number MCP7AM01G1), so I'm not sure what the long constant beep means. I am guessing that the old psu must have taken the RAM (all 4) out with it? How likely is that to happen??? Or maybe it's the motherboards slots for RAM?
I've also tried running it with my brand new nvidia gtx 660, with the same long beeping result

Are there other component failures that can cause this? Could the psu have taken out the CPU too?
Some specs:
CPU intel quad core 8200
Ram: 4 slots, 4 2gb modules. Slots colored in pairs. I guess dual mode or something

Update: I tried a few more permutations of the ram modules and I just got a different beep. This beep is long but not eternal( about 5 seconds) also, this one is a flatter sound compared to the earlier sharp, nonstop beep.

Everything else is unplugged as of now, only psu and mb as I try to just get that short beep of POST success.
Thank you for your help!