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Problem with GTX 660 SLI with Asus Sabertooth z77

Last response: in Graphics & Displays
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May 22, 2013 7:17:20 AM

Hi guys, apologies for the long post (tl;dr see bold text)

I have been running a single GPU set up with the Sabertooth and a GTX660-DC2O-2GD5 since Feb 2013 perfectly fine.
Recently I decided to upgrade to a Dual GPU set up so I purchased another GTX 660 DirectCU II OC card.
This has proven impossible to run due to the PCIe 3.0 x16_2 slot not detecting any one of the cards. I'm unable to see the second 660 in the NVIDIA Control Panel, Device Manager, GPU-Z and Asus GPU Tweaker. I just cant seem to detect anything in the second slot.

I've tried various procedures to try and identify the problem such as:

-Updating graphics drivers
-Placing each card in the first slot; both worked perfectly on their own
-Having both cards in slot _1 and _2 then switching places
-Re-seating them multiple times, checking PSU connectors thoroughly
-Updated BIOS version to 1908, reverted back to 1805
-Placing the cards individually into slot _2 (received no video input, motherboard looped looking for a VGA source)
-Tested alternative PSU (XFX PRO550w)


Now looking around various forums as well as this one, I saw a couple where the solution was to RMA the board, I have done so but requested a replacement instead of repair.
I received the replacement motherboard today, and I'm still having the exact problem.

Looking through the BIOS; in the NB PCIe Configuration the PCIe 3.0 x16_2 slot was marked as ''Not Present'' while slot _1 was marked as x16.

I've contacted Asus Technical Support but their repsonse was to contact my supplier as it seems like the PCIe slot was defective, I have my doubts it is the slot as you've read above I'm having the same problem with a brand new mb.

Any help or solutions would be greatly appreciated as I'm completely stumped.
Thank you

__
-Specs-
i5 3570K
16GB DDR3 1400 Corsair Vengeance
ASUS Sabertooth z77
Akasa Venom 750w Hybrid Modular
Asus GeForce GTX 660 DirectCU II OC x2

Currently running the BIOS Version : 1805
a c 118 Ĉ ASUS
May 22, 2013 7:54:04 AM

Be care full of the bios settings. You can turn that slot off in the bios if your not care full. In the bios video settings for pci should be set to 8x 8x mode.
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May 22, 2013 8:03:13 AM

smorizio said:
Be care full of the bios settings. You can turn that slot off in the bios if your not care full. In the bios video settings for pci should be set to 8x 8x mode.


I havn't changed any setting in the BIOS, and I'm unsure what you mean with the Vvdeo settings; which tab is this setting under. I understand with two cards running it should be running at 8x 8x wasn't aware this was a manual option though?

The BIOS settings are set to default at the moment, is there something i need to change to get the second card/slot working for sli?
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a b Ĉ ASUS
May 22, 2013 8:44:09 AM

have you made sure you connected the SLI bridge properly as well? also, the psu seems suspicious. try both sets of 6 pin connectors and see if they both work
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May 22, 2013 9:12:52 AM

TheBigTroll said:
have you made sure you connected the SLI bridge properly as well? also, the psu seems suspicious. try both sets of 6 pin connectors and see if they both work


I have just re-seated the cards and the SLI bridge again as well as trying both 6 pin PCIe connectors. Still not able to detect anything in the second slot.

I do have an older XFX 550w PSU at hand, would it be worth trying that out instead of this Akasa 850w?
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a b Ĉ ASUS
May 22, 2013 9:51:17 AM

yes. it doesnt sound as sketchy. if the xfx does not have enough 6 pins, use the adpators found in the video card boxes.it should supply enough wattage for now
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a b Ĉ ASUS
May 22, 2013 9:51:21 AM

yes. it doesnt sound as sketchy. if the xfx does not have enough 6 pins, use the adpators found in the video card boxes.it should supply enough wattage for now
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May 23, 2013 9:50:40 AM

TheBigTroll said:
yes. it doesnt sound as sketchy. if the xfx does not have enough 6 pins, use the adpators found in the video card boxes.it should supply enough wattage for now


I'll give it a go, will take me a while to swap out the current PSU since I went fullout on the cable management.
Just as an update, the green power LEDs do light up when plugged into the Akasa PSU; not sure if that means its fully powered though.
I'll update once I've switched the PSU


--Updated--

With the XFX 550w the problem is still there. As with the Akasa both power LEDs on the 660's light up green, load in to windows with only the _1 slot being detected.

I'm not sure what else it could be, unless it's another motherboard with a dead PCIe 3.0 x16_2. Which I somewhat doubt; too much of a coincidence.


____

Went to my local PC store, asked them if they had any idea what the problem could be. They said by the sounds of it's something to do with the motherboards PCIe slot.

I'll be sending it back for a refund, shall be looking to get a new mb away from the Asus brand; since i cant seem to get any sort of repsonse/help from their support section.
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