Problem with new PSU and existing motherboard.

[moonbeamdanser]

I am running a GIGABYTE GA-P55M-UD2 v 1.1 motherboard.  Prior to this I was using it in conjunction with a 500w "Basiq" Antec PSU.  The Antec PSU used the 4-pin connection type.  I now have a new PSU, a 750w Corsair, and it uses the 8-pin connector.

There are several issues I am now experiencing.  The primary concern is when I use the full 8-pin connection, my system will not boot beyond the Windows 7 loading screen; it will go into an endless cycle of rebooting.  At first I thought it was a faulty PSU; to my chagrin after an RMA the issue was still present, so after speaking to tech support with Corsair they said I "should be ok" using only 4 of the 8 pins.

Granted, my system does boot up now that I've gone to the 4-pin config.  But I don't like it; it's designed to take the 8-pin.

Further, upon going to 4-pin, when I shut my system down--it immediately reboots and starts back up again, unprompted, about two seconds later.  This only after initial start-up and then shutdown via the Start menu; if I turn the power switch back on (I have to turn it off manually on the actual PSU to keep it off) it doesn't automatically start back up, then.

Any thoughts?  I've looked at any of the A/C settings in BIOS and none seem to be causing either symptom.

[moonbeamdanser]

*bump*

Also to add: I have done the jumper/remove battery CMOS reset as well to no avail.

[Salmon Trout]

*bump*

We don't like these

[moonbeamdanser]

Thank you, that was very helpful. -_-

[Geek-9pm]

There i s an important detail missing.
Did the motherboard work well before you got the new PSU?

[moonbeamdanser]

Yes, everything worked fine before the new PSU.  (Aside from a known sound glitching problem with this particular model).  It works fine now, aside from the inability to accept the 8-pin and boot, and the inability to stay shut down after shutting down from the start menu.

[moonbeamdanser]

After experimenting a bit more with BIOS settings, I found that "Power On with PME" was enabled.  As far as I know it always had been but had never been a problem.  Apparently the old power supply didn't respond or something, but now the new fancy one does.  Once I disabled that setting it now stays turned off.

The problem with not booting fully when the full 8 pins of the PSU are connected still remains though, and continues to mystify me.

[Geek-9pm]

We would like you to stay here. But this link on another forum you just have to read.
http://www.tomshardware.com/forum/261880-28-power-supply
That was just 4 to 8 pin. What happens if we go 16?
At the rate things are going we will have 64 wire PSU connectors real soon. To match our 64 bit systems, of course.

[moonbeamdanser]

Aye, true, with progress comes the cost of constant upgrades.   Really my concern is just that I have a faulty Mobo to be perfectly honest.  As I said, the Corsair people told me if it works fine with the 4-pin I "should be ok".  Gigabyte with their zero tech support and vague responses to online-submitted questions are no help at all. 

Granted, I do not Overclock my CPU which is what the linked article seems to allude to in order for the lack of 8-pin connectivity to be a matter of concern.  I just don't want to be causing any kind of future damage or malfunction due to insufficient/faulty power supply.

[Geek-9pm]

Thank you for coming back. I have learned some things from this thread. I am going to think twice about baying a Gigabyte mother in the future,. I want support.
My guess is that there is a jumper on the mobo that you have to remove for 8 pin connector. Or they forgot to provide a jumper. Or something like that.

[moonbeamdanser]

You know I hadn't thought of that.  I'm going to pore over my manual that came with it to see if there is something I missed.

And, generally speaking, Gigabyte is supposed to be pretty decent.  Just their tech support is a little sketchy.