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Crossfired PC but no does not post/boot screen

Last response: in Systems
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October 31, 2012 9:09:32 AM

Hello,

Help guys.

I just bought a new MSI 7770 OC PE 1gb GDDR5 128bit card to match my Sapphire 7770 OC ed 1gb GDDR5 128bit card.

Now here's the thing, I tried to run both cards on my Gigabyte 970A-DS3 motherboard (local store and website states that it's crossfire ready)... but it wont post or go the the boot screen. I tried using each card as a solo card and yes they work perfectly fine.

Also, i noticed that I have both cards on the board connected with the bridge and the 2nd card is running without the 6pin power connector and the system will boot... BUT! if I connect the 6pin connector, the system wont boot at all. It will just power the LEDs and fans on the system.

my theory is that it's either the motherboard or the powersupply that's giving me a hard time. but hear me out, i know it's not the PSU as the new 28nm chips are very power efficient (about ~80w max TDP each + fx4100 = ~240w)... but it could still be a possiblity. Need help! I feel I wasted money on something I can't use

to make it more clear, heres my whole specs:

FX4100 3.6ghz @ 4.0ghz
Gigabyte 970A-DS3 motherboard
G.Skill Trident 8GB DDR3 RAM 1600mhz
-MSI 7770 OC PE 1gb GDDR5 128bit << connected to PCIE 16x
-Sapphire 7770 OC ed 1gb GDDR5 128bit << connected to PCIE 4x
HEC Cougar ST 600w


---additional info

I have an extra 400w PSU from my old build and tried using that to power my second card but still the same. still no boot screen or no post screen. I can tell because i have a corsair m60 mouse and if the system is going boot/post, the lights on my mouse will flash.

The method i used to power the second card was using a jumper to boot the 400w PSU by itself w/o another motherboard.
October 31, 2012 9:56:16 AM

Thenfluxx,

Sorry but Hec Cougar Psu`s dont have a very good build quality.
Also the 600w rating is TBH a bit of a Lie it Hits an output of 600W ouput at a peak for about 30 to 60 seconds. The 12v rails are weak to say the least by the time you factor how much wattage and power draw the 12v rails need for the extra 12v cpu connection and the extra 12v power and amps to the Pci-E slots and factor into the 12v the hard drive needs, then workout the power draw and amps needed it wont make a difference if you use another 400w power supply to feed the other 7770. The Hec is out of power and amp output as soon as you put the other 7770 in.
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October 31, 2012 10:16:36 AM

Just had a thought Thenfluxx, it may work as a test to see if the Hec is overloaded.
Take the pins connector from the Hec Psu that feeds the extra 12v needed for the cpu.
Plug the 400w 12v into it instead. and the pci-e extra power supply needed for the other 7770. then your taking load of the Hec get it if it boots all ok you know the problem is the Hec psu.
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November 1, 2012 1:55:36 AM

weaselman said:
Just had a thought Thenfluxx, it may work as a test to see if the Hec is overloaded.
Take the pins connector from the Hec Psu that feeds the extra 12v needed for the cpu.
Plug the 400w 12v into it instead. and the pci-e extra power supply needed for the other 7770. then your taking load of the Hec get it if it boots all ok you know the problem is the Hec psu.


I tried what you recommended but still does not work. I tried all possible combinations with both PSUs connected but still it does not boot or post.

here some other stuff I tried

•I also tried switching and removing my ram sticks but same thing
•Also tried underclocking my cpu for less voltage
•stripped everything to the bare minimum (motherboard, 1 HDD, 2 vga's, 1 ram stick, 1 cpu fan) <also tried the 2 PSU work around
•cleared CMOS

seems all failed. however it is becoming a bit more clearer that the issue is m ost likely found on the motherboard. I have yet to receive a reply from the people from gigabyte to tell me what's wrong with it.

another note: the system wont boot if my PCIE x4 vid card is powered. it runs ok without the 6pin (the fan for the card runs and the whole system boots)

I will try install their new bios from their website and their new bios driver.. I'd hate to buy a new mobo but this build is about 3 months old only.
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November 1, 2012 4:11:36 AM

nevermind I got it to work. gigabyte tech sent me an updated bios that wasn't posted on their site.

benchmarking these babies out right now.

thanks anyways :]
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November 1, 2012 4:39:43 PM

Oh good I am pleased it was a quick fix for you and all is fine.
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!