Graphics card won't 'start' when computer is upright

[redeye_uk]

So I have this weird issue where my GPU won't start/kick in if the computer is upright.

Basically the computer posts, but when it try's to go to the windows login screen the screen doesnt respond (black screen).

Very occassionally it will load, but the GPU artifacts a lot.

However, If I switch it on with the computer on its side then everything is fine.

My theory is when its upright the GPU doesnt sit well in the PCI-E slot.

Has anyone else had similar issue's or able to offer suggestions? This has only started to happen recently

Intel 3570k @ stock
Gigabyte Z77X-UD5H
8GB Samsung Green
Corsair AX750 PSU

 

[redeye_uk]

Thanks. Can't believe how much the card actually flops under its own weight. What are my options for propping it up?

 

[redeye_uk]

Its a 7850, so it's hardly a 'massive' card. In fact, it's a fair bit smaller than the 4870 I had in there previously. It is a Forza III though, so maybe the after market cooler weighs a lot more than standard?

I have a Phantek CPU cooler which is massive and weighs a ton. Maybe this is causing the mobo to flex a bit? I was actually thinking of getting rid of this cooler as it is just silly, and replacing with a closed water loop.

Rather than cable ties or a jack, can't you get a metal bar which runs up the inside of the case which is specifically for supporting expansion cards (I have a Lian Lee A77 case)?