Need help troubleshooting PSU or MB


After scouring the forums for quite a while (but probably not enough), I wonder if anyone has any experience properly diagnosing a PSU or MB failure, or a BIOS problem.

The symptoms:
When switching on the PC, the PSU (Corsair 750 RM) starts to make a clicking noise about once every second.
The CPU and case ventilators work and the drives spin up: Just no image, no keyboard lights.

When I detach all PSU connectors and leave just the ones for the MB (Gigabyte GA-Z97-HD3), the clicking sound is there:
When I detach just the PSU connectors for the MB and leave the others, the clicking is gone (I power up the PSU through the paperclip trick).

What preceded:
A couple of months ago, I replaced the old PSU by this new one. Worked fine till now.
A couple of days ago, I decided to upgrade my antique GT640 graphics card to an RTX3060 Duo.
After inserting the card and connecting it to the PSU, I power up the PC and get a solid red light near the card's connector and no signal out of its HDMI port. I decide to wait for my order of a DisplayPort cable to arrive, the next day. In the mean time I reinsert my antique graphics card and decide to update the BIOS (never know).
I reboot with the new BIOS and all works fine. I quickly check the new card again to see if that helped, but same problem.
I then reinsert the old card and continue working, having decided to wait for the DisplayPort cable. All works fine.
The next day, I fire up the PC again, having changed nothing in the mean time, and the PSU appears to be clicking like clockwork. No display and probably no POST either, since no beeps (although I'm starting to doubt now that there were in fact a couple of beeps during the very first power up that day, but hadn't really paid attention).

Anyhow, now it's like described in the symptoms above.

A bit of TL;DR, I know, but if anyone has any idea how I could proceed from here, any hints are very welcome.



Posts: 856   +206
TechSpot Elite
To get a machine to POST you need
-graphics card if the CPU does not have a built-in graphics card (many don't)
-At least 1 stick of RAM
-PSU connected to the 24pin connector on the motherboard and also connected near the CPU via a 4 pin (or more!). The PSU also needs to power the graphics card in the case of the RTX 3060 (2 x 6pin power connectors on top)
-working monitor connected to the graphics card or the motherboard.

The procedure to reset the BIOS is outlined in the motherboard owner's manual.

If you still have a black screen then it gets tougher from there. You would ideally swap in known-good components to figure out which one is causing you all the trouble. A local little computer shop my be your best bet there.

Thanks a lot for your reply.

I never got the PC to boot when the card was inserted and powered. Works fine when card isn't there.

Before I send the card back, I still have to check whether it's either a mobo compatibility issue or the 750W Corsair PSU not able to perform above 200W (can this happen? Partially failing PSUs? It's brand new.).

Either way, I don't have an adequate alternative PC lying around to test the card and will have to scout for a trustworthy shop...

Thanks again.