I've built a new PC and initially, it managed to turn on. However, it didn't boot properly, showing the CPU (red light) and DRAM (yellow light) indicators. I realized I had forgotten to connect the CPU power cables. After connecting them, the PC won't start at all; it just powers on for a few seconds before shutting off. I'm wondering if my CPU cooler was somehow providing power before, or if my PSU (750W) isn't sufficient for my build. I did check the wattage and it looks like there's more than 100W to spare, but I'm concerned about why it's failing to power the CPU now. Can anyone help me troubleshoot this?
3 Answers
Your PSU should be adequate since 750W is generally sufficient for a system like yours. However, it’s worth considering that even reliable power supplies can sometimes be defective right out of the box. Just double-check that there are no shorts in your setup, like damaged wires or metal touching the motherboard improperly.
It sounds like you haven’t been able to post at all. Have you checked your mobo manual for error codes? If your motherboard has a diagnostic feature, it may give you a clue as to what’s going wrong. It shouldn’t brick from a simple mistake like forgetting a cable, but it’s always good to double-check everything.
According to PCPartPicker, your build is estimated to use around 554W, so a 750W supply should be fine. But the fact that your PC shuts off immediately when you apply power to the CPU is curious. I'd take a look at your CPU installation—make sure it’s seated correctly and that you're using known-working RAM to see if you can at least reach the BIOS.
Yeah, I'm planning on testing RAM from my old PC since it's working. Hopefully, that helps with the boot issue.