If there is no CPU in the motherboard, will the LED still be on?

Question

Sorry if my question may have been answered somewhere else, but my google-fu is kind of weak.

I have been trying to create a new setup recently. The PSU (700W) is known to work on other motherboards, but it is not responding on my new system. The LED won't even light up.

The memory is connected, and so is the CPU (intel i5), and nothing else.
The memory sticks and motherboard are fresh out of the box, however, the CPU was taken from a build where the motherboard has been fried.

When connecting the mobo to the PSU, should the LED in the motherboard still show up if the CPU is non-existent/fried?

Answer 1

Yes, the motherboard LED should light up irrespective of the following:

• CPU is mounted or not.
• CPU is fried.
• RAM is mounted or not.
• RAM is fried.

The LED won't light up on your motherboard if:

• The PSU has a problem.
• The PSU plugs are loose or not connected to all the power inputs on the motherboard.
• One or more of the PSU output wires is damaged.

In your case, yes the Motherboard LEDs should light up. Get a multimeter and check your outputs!

Answer 2

As someone who has just done their own build I can say for fact that the LED on the motherboard should light up even if there is no CPU or no anything for that matter. All the LED needs to light up is for your PSU to be connected correctly to your motherboard.