motherboard onboard VRM controller chip fails?

[eccerr0r]

Is having the VRM controller chip fail (without the mosfets failing) common on motherboards?

I think i found one of my boards with one high probability failure, and another suspected failure... both boards don't give vcore anymore... (both S775 boards incidentally...)

[corl45]

Unfortunately I am not sure how common this failure mode is. But I do have a board that has symptoms of of VRM issues but all the VRMs themselves are checking out. Can you confirm what tests made you think the VRM controller failed?

[momaka]

Check if the VRM controller is getting its Enable signal.

Could also be bad BGA under the 775 socket - fairly common if a stock Intel push-pin heatsink was used, since they tend to warp the shit out of any motherboard (not that s478 or AMD's 754/939/AM2/AM3 stock heatsinks don't, but they usually aren't as bad.)

[eccerr0r]

hmm trouble there seems to be something leaky on vcore and it didn't seem like it was the mosfets. Not sure what else is connected to that vcore wire when the cpu's not installed...

[ChaosLegionnaire]

for me, its my socket 478 875p chipset boards and one s939 asus a8v board.

the s478 875p chipset boards give a too low value for vcore on power on. the cpu vrm output reads 0.33v to 0.35v on one board (asus p4c800-e deluxe) and 0.87v on another board (msi 875p-neo2 and asus p4c800 non-deluxe). it always gives this vcore voltage reading regardless of the cpu inserted so its the vrm regulator. i dont think the socket is bad because i've never used the stock intel heatsink on the board. i've used a third party cooler which doesnt warp the hell out of the board. it also has a backplate regardless, so it shouldnt mangle the socket at all.

while another s478 875p chipset board (abit ic7-g max II) randomly powers off by itself after running for a few minutes. not sure whats causing it. its not the psu because i swapped the psu but this issue still persists. the psu can still power a s775 quad core system so its not the psu, its the board.

for the s939 a8v board, the vcore randomly starts decreasing after a few mins after power on, until the vcore reading is too low, it hangs the system & cpu because its too low. not sure whats causing it, bad caps on the cpu vrm or a bad vrm regulator. sometimes, the opposite happens, i see the vcore reading go higher and higher. cpu still runs fine tho. not sure if it will fry the cpu. also sometimes, the board randomly powers off itself when i keep pushing the reset button over and over again to try to get the system to post when the vcore is too low.