Can't get the video card to sit properly

I (think) I am having an issue getting my video card to sit properly in the motherboard. Sometimes it will post, sometimes not.

I just built a new system. Had an issue from the start, and had to rma the motherboard. New one worked ok, but as soon as I hooked up the hard drive, then it wouldn't post anymore. Decided it was the PSU and rma'd that.

So now finally have a new psu, and have it hooked up, the problem now is it only posts sometimes. I think the issue is that the video card does not sit properly. If I re-seat it, then sometimes it works, sometimes it takes a few tries. If it works one time, even if I touch nothing but the power switch to turn it off and back on again, it will not work the next time.

The motherboard is not in the case atm, it is currently sitting on a piece of cardboard for testing.
I am wondering if anyone has any suggestions on how to get the video card to sit properly. Or if it just should work all the time once it is in OK? I have the sapphire hd 4890, and it is big and heavy. when I put it in it, it tends to lean over. When the mb was in the case ( I took it out after it was only posting occasionally, it would work in there, just not all the time) the video card would work if it was not completely straight (and not lined up with the screws on the case so I couldn't screw it in to hold it in position). Out of the case, I have pen underneath it to hold the card in position.

Like I said, I am not 100% sure that is the problem, but it seems most likely the reason for my woes.
Or could it be bad connectors on the video card (or possibly mother board?) that makes it work sometimes and not always? Because of the other rma's I've had it's been over a month got the video card so I don't know if I can return it for another.

new build (or attempted build) parts:
MB: EVGA 132-BL-E758-A1 X58 3SLI RT
CPU: INTEL|CORE I7 920 2.66
PSU: PSU ANTEC | SG-850 850W
Video: Sapphire HD 4890
HD: Western Digital Caviar Black WD5001AALS 500GB
Mem: Corsair XMS3 Tri Channel 3GB (only 1 stick is in right now)

checklist - yes

except # 4. Did you verify that the video card is fully seated?

I have put re-seated it a few times, and like I said, sometimes it works (posts completely works fine) and then the next time it will not. So I think that the video card is not STAYING connected properly. I am not sure why. I have installed video cards a bunch of times before and never had this much problem, so not sure how to make it stay, or if there is actually a problem with the card connectors.

Sometimes they don't seem like they want to line up with the bracket screw. You can make the card straighten up and then secure it down with the screw.

Are you using the right motherboard standoffs?

Hello hello hello! Does no one read any of the other posts?

THE CARD IS DEFECTIVE.

Sorry, for snapping...

I will let you know the status when I get the replacement (2-4 weeks!)

Meanwhile, the replacement card - ASUS EN9600GT Silent, works great. It is a lesser card, but I think I like it better. It is silent and cooler.