I have this PC with an Asus P5N32-E SLI motherboard and an Intel Q6600 CPU. I got a new RX-5300 PSU, but it didn't work.

• The motherboard power LED is on fine
• When I switch power on, the PC powers up briefly (0.5-1 sec) then shuts down
• From there on out when I switch power on, it stays on, all fans and components seem to be receiving power, but the motherboard won't POST. No video output, no PC speaker beeps, nothing
• If I turn the hard switch on the PSU off and then back on again, go to step 2; The PC turns on and then off immediately again, and on subsequent power-ups it stays on but won't POST

I disconnected every component but the motherboard, CPU and PSU. Still nothing. I tried three other models of PSU on this PC, both of higher (600) and lower (<300) wattage than the 530 on the RX-5300 and they all work fine.

At this point I was convinced the PSU was faulty so I returned it. When the replacement arrived, it behaved exactly the same. So two different units of RX-5300 both with the same symptoms, neither working with this motherboard + CPU. Yet, three other models of PSU work perfectly fine. The PC store couldn't reproduce my problem with the returned PSU.

I tried resetting the CMOS with the jumper. I tried with both the 4 and 4+4 (with and without the extra +4 connected) CPU connectors (curiously the RX-5300 comes equipped with both).

Could it be a statistical probability that I get two units of the same model of PSU that are faulty in the exact same manner? Could the RX-5300 model itself be somehow incompatible with this motherboard? I was under the impression that PSUs were pretty much universal so long as you have the wattage. Could the motherboard be broken in some such a way as to work with certain PSUs but not others? What's going on here?