Computer won't boot. Dead CPU or Mobo?


Junior Member
Sep 18, 2017
Hey guys, I'd like you to help me with a question I'm having about my PC.

A few days ago I was on Youtube, the PC (described below) turned off out of nowhere, I tried to turn it on back but shutdown in 5 seconds. I tried to turn on again, but now the CPU_LED is stuck and I can not POST or even enter BIOS!

PC Description:
CPU: i7 870 STOCK
RAM: Corsair 2x4GB 1333mhz
Source: XFX 550W PRO Core Edition
VGA: GTX 760

Here's what I've done:
-Reset BIOS either by removing the battery or by moving the jumpers
-I tried my PSU on another PC, and it works perfectly
-Booting the PC without memory = According to the manual, it should beep, but it didn't.
-I tried my memories on another PC, it works.
-I checked CPU and still warm up, dunno if it's related

The most curious is that, if I turn the PC on without the 8-pin connector on the processor, the PC turns on, the LED light on the CPU goes off, but the PC shuts off shortly thereafter. If I boot PC with the 8-pin connector, it gets CPU_LED on, but if I keep the 8-pin connector and take out the CPU, it's still the same, almost as if the processor was never there at all.

The manual says that if you connect the mobo without the memories, the PC should beep, but it didn't. In other forums that I researched, turning computer ON with no CPU nothing happens, does not POST (obvious) but also does not generate beep or anything, even if everything is OK.

So, what might have died? Processor or motherboard? Has anyone went to something crazy like this?


Golden Member
Jan 8, 2013
Try the CPU on another board. Make sure there is thermal paste between the CPU and the cooler. Disconnect the speaker from the system. Take a 1.5 volt battery briefly touch the speaker leads to the + & - leads. Does it make a noise or clicking sound ? If yes, the speaker is good.