Replaced CPU, fans turn on but PC doesn't power on.

[OMGJJ]

GTX 1080

16gb ddr3 ram

msi z87 g41 motherboard

I had an i5 4670 and got an i7 4790 to replace it. I put the new CPU in, applied thermal paste and attached the cooler.

Now when I press the power button on my PC all the fans start spinning, the LEDs on my GPU turn on but the case light doesn't turn on (usually the power button lights up when the computer is on) and nothing appears on the displays.

I have reset CMOS, taken out the motherboard battery for a few minutes, reseated the CPU.

I have also put the old CPU back in (the computer works fine when I do), and updated the BIOS. Is the new CPU broken?

 

[mdd1963]

reinstall the original...if it still works, your rig is fine.

Retry 'new/suspect' cpu, making sure CPU fan connected to correct header. (I take it the CPU is not exactly 'known good', but a recent purchase?)

 

[OMGJJ]

reinstall the original...if it still works, your rig is fine.

Retry 'new/suspect' cpu, making sure CPU fan connected to correct header. (I take it the CPU is not exactly 'known good', but a recent purchase?)

The original works fine, so I know the rig is ok.

The new CPU is second hand but the seller says it works fine and was selling it for an upgrade. I don't have a second motherboard or anything like that to test it in. There don't seem to be any bent pins on the CPU.