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790fx-gd70 - New Mobo - Wont boot

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November 24, 2009 3:31:48 AM

I'm curious if I have a bad mobo. I have everything installed and checked but I get NOTHING when i hit the power switch on the front (nor the reset switch in case that was somehow swapped with power improperly). The only thing I have is an LED power switch on the mobo that the book says is main power. That one is glowing a nice green and does nothing when I push it. It also has a reset switch on the mobo so I pushed that one too. No fans fire up anywhere either and no HD spins. I know the power supply is good because I just changed motherboards and it was running a few minutes before.

Other things I checked:
* Main power to mobo - check
* CPU power to CPU on mobo - check
* all those pain in the ass leads from the power switch, LED, HDD LED, Reset SW and SPKR - double checked (and flipped +/- just to be sure)
* Memory in and double checked for seating - check
* Power and SATA cables to HDD(x2) and DVD
* Power to 3 fans including CPU - check
* Video card seated and both power leads to card connected - check
* USB front leads to mobo connections - check
* Front audio connections to mobo connections - check
* Power from wall to power supply - check
* Power switch on power supply on - check (I have LEDs on the mobo showing power also)

In any case, I've built tons of systems since the 286 days so I'm not a novice, but I'm stumped. Anything special about these high end boards I should know?
November 24, 2009 3:59:04 AM

Interesting.. It had something to do with the CPU ATX 12V power connection. When I deinstalled the power to it, I got life. Not sure why, but when I reconnected it everything is running system checks (lots of flashy lights) and looks normal. I guess I found my answer but figured maybe someone else will have the same issue and this will help them.
-Toysmith
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December 25, 2009 12:07:22 AM

I have the same prop with my 790fx-gd70 mobo. Im running a phenom II 955 black edition and win7. I did a biosupdate using msi liveupdate and then looked at my biossettings, didnt change anything though (exit without saving). When I was done with the bios and wanted to boot up win I got a bluescreen and my pc died. I have tried everything. The damn thing is dead as long as I have the 12v atx cable connected. The comp fires up when I remove it though, although that doesnt help me... I need my cpu! Any ideas anyone?

Thanx in advance / alexander
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December 25, 2009 2:24:36 AM

My problem was that the 12v connection next to the CPU was incorrectly installed. On the power supply I'm using it has two "halves" and you hold them together and then plug them in. What was weird is that you can hold them side by side two different ways. The one way that looks wrong is the correct way (a bump on the outside of the little square fitting...). Put the two bumps together even though they don't sit flush, then plug them in again and make sure they are firmly seated. That solved my issue.

As for the bios, I had no reason to update it and mine works fine. You should only update it when you need to. Not sure if you can find the original bios and restore it, but it sounds like you may have a bad install of it. Try flashing the bios again. Sometimes they just don't take and you can redo them. First try getting your cpu power connected as that may actually be your issue.

Good luck.
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December 25, 2009 9:23:17 AM

I did a biosupdate because ive read abot the old bios and the 955 not working all that good together. My cpufan was constantly spinning at over 6krpm and the cpu temp was around 50-55 for some reason. Thats why I did the biosupdate, i shouldnt have though :(  are you talking aboutthe pci express (gpu) power cords? Ive tried that but it doesnt fit. Ive tried the clr cmos, moved the jbat plug, removed tha battery. Nothing seems to be working.
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December 25, 2009 10:51:42 AM

Actually there is a 2nd set of connectors (its like a 4x2 and a 4x2 plug that mate together to make one 8x2) Your power supply may have an 8x2 or two 4x2 grouped together.

Those go in #12 (see the diagram at http://www.bit-tech.net/hardware/motherboards/2009/05/0...).

As for the reason for the update, that makes sense. Mine was ok. I got lucky. I have had 2 freeze ups in the last month but I was gaming so I'm not sure what happened. My CPU is running right now at 36 at idle. Check that ATX 8x2 listed on #12 on the page above.

Hope it helps.

Eyeleks said:
I did a biosupdate because ive read abot the old bios and the 955 not working all that good together. My cpufan was constantly spinning at over 6krpm and the cpu temp was around 50-55 for some reason. Thats why I did the biosupdate, i shouldnt have though :(  are you talking aboutthe pci express (gpu) power cords? Ive tried that but it doesnt fit. Ive tried the clr cmos, moved the jbat plug, removed tha battery. Nothing seems to be working.

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December 26, 2009 9:53:15 PM

Toysmith is right, the CPU power connectors have to be properly mated in order for it to work properly, every manufacturer uses a different method it seems but two 4 pin connectors will make one 8 pin.

That doesn't seem to be your problem though Eyeleks, it could be that you have too much thermal paste applied or in the absolutely worst case you used a thermal paste that conducts electricity and you got it some where you shouldn't have. If the CPU gets too hot your computer will blue screen and shut down w/o warning, it won't let you kill it.

If that is your problem make sure you run CPU-Z so that you can check for any physical damage to the CPU. Speed Fan will also help you thoroughly check for any abnormalities.

Hope this helps!

BTW the required update for the AMD was the 965 BE 125W w/ the new c3 stepping. It's a pain because you need a preexisting AM3 CPU to do the update, you can't just plug and play the 965 BE 125W, and yes it is different from the 140W the 140W is just an overclocked 955 BE.
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