Question about Intel ASUS P4C800-E Deluxe 875P Socket 478 DDR 400 ATX Motherboard 3-in-1 Combo (MP4C800EDLXCOMBO)
Can't start system. If 12V2+2 connector plugged into MB, PS_ON goes back high right after going low. If 12V 2+2 not plugged in, power stays up, fans run, voltages check OK. All true with peripherals removed, only CPU and a couple HDDs to load the PS.
What conditions cause PS_ON logic to reject power when 12V2+2 connector is connected?
No need to get testy--no pun intended--I do appreciate your thoughts and help. What I want is to save the MoBo if I can. I'm sure it is deciding to turn off the PSU for a reason. I know the PSU will shut down if there is too much current draw, but I don't know what bad conditions the MoBo will use to shut down--probably voltage not reached in x msec, maybe overvoltage, and maybe in my case, the logic chip that ands the necessary conditions together and latches PS_On low is burnt. Today I'll try tracing the 12V from that connector on the board--probably doesn't serve much more than the CPU. Maybe I can find something.
Posted on Nov 24, 2007
Usually it is over-current that will make PS_ON go high. However, the opposite is true: if not enough load draw, PS_ON goes high and never goes low. Not exactly certain about link to 12V2+2 connector, although same theory may apply.
Posted on Nov 20, 2007
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