General troubleshooting tips for ASRock Z170 ITX/ac Motherboard

just got a 'new' (probably isn't) RMA return for my Z170 ITX/ac from ASRock. My previous mobo failed when it quickly degraded to the point of no power routed to CPU or CHA1 header fans. However, in trying to bench this new one, I still can't get video (one of the original things that started happening to the old mobo). When I talked to ASRock prior to the RMA, they assured that the new one would be fully tested prior to shipping. So now I have to figure out what I'm doing wrong.

I've tried each of my two sticks of RAM, in each of the two slots. Aside from that, the only things I have connected are the 24-pin power and CPU power from the SF450 PSU; the power switch header from my NCase; PS2 keyboard; and DisplayPort (and I've tried both HDMI ports, as well). When pressing the power button, the CPU fan runs for about a minute, and then it seems to reboot itself. I don't know if it's a failsafe in the motherboard or in the PSU. Either way, video doesn't even try to come on.

Note that prior to sending out my previous mobo, I was able to at least get to get BIOS, so I don't think it's my PSU (Update: just tried another PSU, I really don't think that's the problem). The only other thing that I don't have the ability to swap out is the CPU. But even if it were the CPU, wouldn't I at least get some attempt - unless it was just that badly gone, I guess. I don't know, looking for any kind of suggestion that could help pinpoint where things are going wrong.

Thanks!

I'm not seeing where you mention having the 4 pin cpu cable attached. Is it?

MrGreg62 said:

...4 pin cpu cable attached.

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Do you mean the CPU fan? From the PSU, there's only an 8-pin EPS, and that is definitely connected.
But yes, my CPU fan is attached. I've tried both an NH-L9x65 and a NH-C14 (which is 3-pin, to be thorough, but that shouldn't be a problem).

Okay I was referring to the EPS cable because you didn't mention that it was connected in the first post wasn't sure if it was 4 or 8 pin on an itx m/b. Try clearing the bios. Also even seasoned system builders have an occasional brain fart so I have to ask are you sure you don't have a PCIe cable mistakenly attached to the 8 pin socket?

MrGreg62 said:

even seasoned system builders have an occasional brain fart so I have to ask are you sure you don't have a PCIe cable mistakenly attached to the 8 pin socket?

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Agreed, and appreciate the runthrough for that exact reason.

EPS and PCIe are keyed; can't interchange them. Plus, when I used another PSU to rule it out, they had labels directly on the cables and it still didn't work.

Sadly, clearing the CMOS is of no help, and I still can't even get BIOS to load. It's looking like a CPU issue at this point. It and the mobo are the only two items I don't have the ability to swap out, and with the mobo replaced (taking ASRock at their word that they hand-tested it before sending it to me), it's the last component to scrutinize.