Gigabyte GA-MA770-US3 - No Boot/ Fan Cycling

[socketa]

Had this Mobo for a while as main computer.
Over the past half year, every several days, the screen would just go blank.
But today it automatically did a complete systematic shutdown all by itself.
( i mused over the thought that it might be a hacker shutting it down)
When i turned it back on the fan 'cycles' from normal to high speed (you can hear it)
So i pulled out the graphics card and swapped the PSU - Same story
Then i checked out the power plug at the front panel connecter area, and noticed that it turned the computer on when i reconnected it.
So i measured it's resistance - 2000k
(Didn't think that these momentary power buttons could develop a low resistance fault)
Used another power switch, which tested good - but the fan still 'cycles' and no BIOS beep.
It also wont shut down by holding in the power button.
Any clues as to what's going on here?

[jega]

Re: Gigabyte GA-MA770-US3 - No Boot/ Fan Cycling

Hi!
You can try to measure voltage on pwr button connector on motherboard. If voltage on red wire is less then 2V then you have dead Super IO controller on motherboard. All you said indicate this is the reason of all symptoms. Try to touch super IO with finger (but carefuly after 15-20 sec after power on. It should be hot or veeeery hot.

[socketa]

Re: Gigabyte GA-MA770-US3 - No Boot/ Fan Cycling

Thanks
There is 5V on power button connector
The Super IO Controller chip doesn't even get warm when the board is powered up.
Now the CPU fan has stopped 'cycling' and runs at normal speed

[socketa]

Re: Gigabyte GA-MA770-US3 - No Boot/ Fan Cycling

Noticed that the NB and SB heatsinks are reasonably floppy, the two diagonal spring retainers don't seem to be a too great of an idea.
Did some searching, and apparently they are meant to be like this!
But, as a result, i think that they could quite possibly be fried.
At least there's some good caps on the board that can be salvaged.