What Happens if I power on without CPU?

Aaralli · January 19, 2020

I'm in the process of building a new PC, and I have every part except the CPU, which will be either a Ryzen 7 3800x or Ryzen 9 3900x, and the GPU, which will probably be a 2080 SUPER. I kind of just want to see what my new Corsair QL fans look like really quick, but would that be bad for the computer overall?

Mister Woof · January 19, 2020

never tried it. prob. power on but nothing will actually do anything else

Lurick · January 19, 2020

You might get power to the lights or you might not but you won't kill anything.

Aaralli · January 19, 2020

Just now, Lurick said:

You might get power to the lights or you might not but you won't kill anything.

Okay, thanks. I'm going to try it. Wish me luck!

Windows7ge · January 19, 2020

If computers haven't changed much in the past 10 years when it comes to powering it without a CPU the answer is it won't POST. It will sit in a sort-of "pre-POST" state powering the devices. It will stay like that until you hit the power button a second time where it will shutdown immediately.

Short answer is it won't hurt the system at all.

TomvanWijnen · January 19, 2020

I once put an LGA 775 CPU in an LGA 775 socket that had a different chipset than the CPU needed. The computer did not boot to anything, but the fans did turn on. After I put the old CPU back in, everything worked just fine. I later put the CPU that didn't work in that system in a different motherboard where it's now been in and worked for many years. If things haven't changed since, I don't think anything bad would happen. Do make sure no dust can get in your socket.

Aaralli · January 19, 2020

10 minutes ago, Windows7ge said:

If computers haven't changed much in the past 10 years when it comes to powering it without a CPU the answer is it won't POST. It will sit in a sort-of "pre-POST" state powering the devices. It will stay like that until you hit the power button a second time where it will shutdown immediately.

Short answer is it won't hurt the system at all.

Right, I knew it wouldn't POST. I honestly just wanted to see my fan LEDs in action for the first time, since it might be another months or two before I get my CPU.