I have 2x GTX980 in my setup, watercooled.

About 8 to 12 months ago, i had one of my cards RMA'ed due to coil whine. Everything has been fine, but latly, my PC has started to spass out. When its been off, i turn it on and i shows bios boot and then nothing.. i can then press restart, and the pc will boot into windows no issues, then everything runs fine. Gaming wise, i have been playing Postal 2, (old game, nothing fancy) but its been crashing out.

I attempted to set my second GPU as main card, and this seems to solve the issue, apart from a few small issues with useing the second GPU as main card, it all works.

Well i went on to format, this made things worse. I can install my GPU drivers on almost every single boot up now (with GPU1 as main) no issues once more with using GPU2.

The GPU 1 is the card i got after my RMA, does this sound familiar to anyone? Its kind of a pain with full custom loop, so i want to test this to death before i RMA the card.

need to post system specs  like mobo-psu and all.    I assume you use a quality psu with enough watts to hold up to a strong SLI set up  or maybe a budget 550w that's just wigs out under full load stress over time or what ever ? 

Pierre3400
When its been off, i turn it on and i shows bios boot and then nothing.. 

Are you running a overclock on your cpu? If yes, set your bios back to default settings and retest the system. Let us know if you continue to get stuck at post or not.
 

Pierre3400
Good deal, I did some 3Dmark Firestrike benching ealier, not problems getting through the tests, but the GPU Max was very unsteady, between 95 to 99% load.
Switched over to running GPU2 as main, and it ran about the same score, but rock solid 99% on the GPU load, there is deffo something fishy about my GPU1 card.

Might be something going on with the pci-e slot on the motherboard. Sounds like you'll need to test each card individually in the same pci-e slot.
 
 

You can also Remove your PCIe Power Cables and reinsert the them and make sure the Click in and Locked.
Check for any Pins that may have been push out of the PCIe Power Cable and check the connectors are click in and locked on the PSU Side.
 
I go so far as Putting the Serial Number of the Other Card in the Support Ticket that started the RMA in the beginning.
 
Make sure that Both Cards show under My Products and are Still Covered by a Warranty.
Maybe one of the Cards are not covered under a Warranty any longer.
Both Cards must be covered in the Warranty to cover replacement of an SLI Setup.

Dave3d
Wow.
Another X99 mobo system getting all kinds of freaky with a 900 series card.
....

I ran My EVGA X99 Classified Motherboard with 4 GTX 980 HC Cards for over 2 Years almost 24 hours a day with Zero Issues.
Today I am running a pair of 1080 Ti KB HC Cards on that same motherboard.