Evga 780 TI problem w/ Asrock, Gigabyte and Asus MOBO

[eox08]

Hey everyone, I'm needing some help understanding what my problem is. First off, last year I upgraded my GPU from a nvidia 260 to an evga 780 TI. My problem comes with the motherboard not registering the GPU in it's primary PCIe slot (I've disabled the on board graphics with all motherboards with no success.) What baffles me is, if I throw the 260 in the primary slot it works just fine (on all 3 motherboards) but if I throw the 780 I get nothing. No detection. However, if I place the 780ti on the last PCIe slot it works just fine (on all of the motherboards as well.) I'm trying to understand why this is the case. I feel like my 780 ti GPU isn't getting used at it's full potential since it only runs at 4x speed. I have updated BIOS on all of the motherboards each and every time I swapped them out. I figured the motherboard may be a problem and that's why I have purchased so many (not the wisest decision lol, plan to sell them or make another build for a friend.) CPU wise I am running the Sandy Bridge intel i7 2600k (LGA 1155), 14 Gigs of ram, windows 7 64-bit professional. Right now I have my Asrock z77 Professional Fatal1ty in with my i7 2600k with my evga 780TI in the bottom pcie lane. I also have the Asus sabertooth z77 collecting dust and the Gigabyte collecting dust as well. Honestly, I would just like to use my evga 780 TI GPU in the primary slot on one of those motherboards. I'm not sure if anyone has any knowledge as to what is going on exactly but I would appreciate help.

I know for fact my evga 780 is not faulty. As I have been able to use it on the last PCIE slots on all three motherboards (just never the primary)

I know the primary slot is not faulty on all 3 motherboards as my older 260 and 550 ti cards work flawlessly on all primary PCIE lanes on all 3 motherboards.

Thank you for taking the time to read my issue!

Here is the link for all of the motherboards I have ready to use if this sheds any light.

Asrock - http://www.asrock.com/mb/Intel/Fatal1ty%20Z77%20Professional-M/

Gigabyte - http://m.newegg.com/Product/index?itemnumber=13-128-498

Asus -
http://www.asus.com/us/Motherboards/SABERTOOTH_Z77/

 

[JackNaylorPE]

How did you manage 14 GB of RAM ?

PSU ?

 

[eox08]

Lol I know, the RAM add up is different, 3- 4 gig sticks and then one 2 gig stick

PSU is Corsair RM 850w

 

[EasyLover]

Please clear the BIOS of the mobo. Also, are you getting blank screen on the monitor when connecting the GPU on first PCIe slot or you got the issue after POST

 

[cowboydude99]

If the computer won't POST with the 780ti in the primary slot on 3 different motherboards I would point the problem to the GPU. Maybe a damaged pin or something that is being used by the x16 slots instead of the x4?

I honestly cannot say what the issue is, but with the facts you've listed the only common thing is the GPU.

I would remove all the RAM for testing - except 1 stick.

 

[JackNaylorPE]

You want the memory installed in matched pairs

RM series is questionable (caps)