tl;dr: PC dead after Stand-By, no beep code, no post, no signal. Help?

Hello,

I built a cheap PC for my friend out of (mostly) used parts. He wanted something to game on for 250€ , so I got the following parts:

Acer Veriton M290 Bundle (Case, i5-2400, Mobo [H61H2 AM v1.1], Cooler Master low profile CPU Cooler, 8gb 1333mhz Ram, DVD drive)

--> used

R9 270x, used

BeQuiet System Power 8 600w, new

1TB HDD, new

Thursday everything was working fine. The PC beeped once after pressing the power button and started normally. Today he was watching some videos on YouTube and then put the PC in Windows 7 Stand-By mode.

After ~half an hour he wanted to wake up the PC, but it didn't react. He then rebooted it several times using the power button on the front and the power switch on the psu on the back, but every time: fans spinning, power button glowing, no beep, no signal. He then called me and brought me the PC, and I began troubleshooting.

I tried:

• powering it on just like that

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on w/o graphics card

Result: Fans spinning, no beep power button glowing,, no signal.

• powering it on w/o RAM

Result: Fans spinning, non-stopping beep, power button glowing, no signal.

• powering it on w/ 4GB RAM, Slot 1

Result: Fans spinning, non-stopping beep, power button glowing, no signal.

• powering it on after putting SAME RAM-stick in SAME slot again

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it with every thinkable combination of the two rams ticks and one i had lying around

  Result:

1. First: non-stopping beep, power button glowing, no signal
2. After SAME sticks in SAME slots: Fans spinning, no beep, power button glowing, no signal.

• powering it on after resetting cmos (battery out, 5 minute wait, battery in)

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on after resetting cmos (jumper on reset pins, 5 minute wait and jumper back in original position)

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on w/o cmos battery

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on w/ other cmos battery

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on w/ other graphics card

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on after pulling out every cable and putting them back in

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on w/o any drives

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on w/ another PSU

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on after checking mainboard stand-offs (everything as it should be)

Result: Fans spinning, no beep, power button glowing, no signal.

• powering it on without power button

Result: Fans spinning, no beep, no signal.

• powering it on using combinations of the above mentioned things

Result: Fans spinning, no beep, no signal.

All the tinkering was of, course done, while the PSU was off and the power cable disconnected. I do not have the parts to check the Mainboard with another CPU or the CPU with another Mainboard. I suspect one of these is dead. And I'm kinda out of ideas of things to try.

Please tell me if I overlooked something obvious or if you know what could have caused the PC to go all "Sleeping Beauty" on me.

Thanks in advance!

MfG Erik