Computer Turns On But Won't Display

[spirits77]

I have an Acer Predator G3620 - UR308 since 2012, and now it won't display anything. I have tried everything at this point. So I was wondering if you guys could help me diagnose the problem.

Heres the stuff I have tried:

I have tried replacing my power supply with a new one, which didn't work.
I reseated everything and still won't work.
I replaced the bios chip, didn't work.
Drained all the power via power button, didn't work.
I know the motherboard isn't dead, because when I take out the RAM, it starts beeping.

IMPORTANT: There have been times when I would play around with the inside the components and rarely it would beep then turn on, however it would be very slow. This happened a few times which took so long, however I checked how much ram was detected and it only showed 4gb, but I have 12gb installed, so I feel the problem is the RAM. Also when I went to open a game the computer shut off.

It can't be the motherboard because it beeps whenever I take the ram out right? I know it's not the cpu and graphics card.
So it has to be the RAM right?

Some notes: whenever I do turn it on the hdd light doesn't show, but all the fans spins, however doesn't display.

Hypothesis: I assume that the ram is dead or is barely making it, because I have an old 500w power supply which diminished in voltage over the years, so maybe the power supply killed the ram? Does it sound like a RAM problem?

Specs:
I7-3770
12gb of ddr3 ram (Kingston)
Gtx 670

Thanks for taking the time to read!

 

[buldokus]

Its unlikely that all sticks would die at once so unless you havent already try all the slots with each stick until it starts working. If it doesnt ....then u might have a faulty memory controller.