Agree with the above..disconnect the SATAs as a start to see if that resolves it. Both power and sata cables.
Check all power connectors into the motherboard..I'd probably reseat them to be certain. I'd assume a 4/8 pin along with the main power connector and if no onboard power button, ensure the headers are in correctly. And if you have a modular PS, ensure the connections there are in snuggly (again, reseat for certainty). I wouldnt think this would be it, but make sure the power cable from the PS to the wall is also in securely at both ends (and if your PS has an on/off switch, check that its on...obvious, but it can get missed). Basically, check all cables/points of failure to get power to the board.
Would also make sure the MB is sitting in your case properly..not touching any metal and is on the standoffs properly..if you can take the mobo out of the case and still get the headers from the case to connect for power, id do that as a sanity check.
After that..you can check the power supply itself..paper clip test is an easy enough test.
Check all power connectors into the motherboard..I'd probably reseat them to be certain. I'd assume a 4/8 pin along with the main power connector and if no onboard power button, ensure the headers are in correctly. And if you have a modular PS, ensure the connections there are in snuggly (again, reseat for certainty). I wouldnt think this would be it, but make sure the power cable from the PS to the wall is also in securely at both ends (and if your PS has an on/off switch, check that its on...obvious, but it can get missed). Basically, check all cables/points of failure to get power to the board.
Would also make sure the MB is sitting in your case properly..not touching any metal and is on the standoffs properly..if you can take the mobo out of the case and still get the headers from the case to connect for power, id do that as a sanity check.
After that..you can check the power supply itself..paper clip test is an easy enough test.