Question MSI Z790 Carbon WiFi will only power on by using the BIOS Flash button ?

Dec 28, 2022
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Dear forum members,

The motherboard in question can’t boot by using the case power button or by shorting the power pins on the board. The only way to boot the board is to have a usb drive with a BIOS file connected to the usb bios port and pressing the BIOS update button on the backpanel. It will flash the BIOS and restart. Still, no way to normally boot the board afterwards. I’ve disconnected every device from the board so itˋs only the psu and the board. Using Seasonic SS-660KM which works fine with my old build.

Any suggestions or is this an rma case?

Sincerely,
Grigori
 
Dec 28, 2022
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1
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Hm? Those new boards are not supposed to power without CPU. Install CPU/cooler/RAM and then try it.

Did that too. Tried booting with cpu/cooler/ram installed. No cigar. It will only boot via pressing the BIOS update button on the back panel. Will not boot via case power button or shorting the power pins on the mobo.

Such a weird behavior.
 
Did that too. Tried booting with cpu/cooler/ram installed. No cigar. It will only boot via pressing the BIOS update button on the back panel. Will not boot via case power button or shorting the power pins on the mobo.
Flashback button does not really power up whole board though, just a couple of circuits necessary to update BIOS. So it is quite possible that the some parts of motherboard are not working. Theoretically you could try jump-starting PSU while it is connected to motherboard, but even if that would work it would mean motherboard's start up circuit is bad so no real point of doing that. I guess it's RMA time.
 
Dec 28, 2022
6
1
15
Flashback button does not really power up whole board though, just a couple of circuits necessary to update BIOS. So it is quite possible that the some parts of motherboard are not working. Theoretically you could try jump-starting PSU while it is connected to motherboard, but even if that would work it would mean motherboard's start up circuit is bad so no real point of doing that. I guess it's RMA time.

Thanks for sharing the thoughts. My thinking as well. Guess the only thing left to do is to try another psu, reattach the bios battery, etc. After that - rma time.
 
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By the way guys, do you find the psu mentioned above to be too old, i.e. might it be too worn out to perform at the spec with the new hardware?
It should not matter for your problem - if it works it should be able to power the board no problem - even if it might fall short for the setup at full usage (which is possible especially if you would like to run CPU without power limits).
 
Dec 28, 2022
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Actually I must apologize to everyone who took their time to look into my problem. The PSU is in fact a 760 W model, namely an SS-760KM. This wasn't intentional, by any means. Discovered this by accident, since two 8-pin CPU power cables are included, and not one, as is for the 660 W model. Anyway...

Thank you all for your time and friendly advice, I'll tinker some more and most probably will have to continue using my old rig.

This is a very friendly community!