GPU stopping hp from posting?

[herb]

So recently I was fixing up an hp rp5800 desktop (pretty much an elite 8200 just for POS integrators) and everything was going super smooth. However I needed to update the bios to get support for the CPU I wanted to upgrade to. After I updated the bios the PC gave off some really strange symptoms.

 

The first thing it did was turn on and rev the fans all the way up and then all the way down over about 30 seconds and then it just went straight into windows without a post screen. After that it wouldn't post at all and it just seemed kinda stuck.

 

After that happened I took all my upgrades out and started putting them back in one by one. After putting everything back except my GPU (I'm using a GTX 745 by the way) the PC worked fine. However once I put the GPU back in, the PC booted fine 1 time and then after doing a restart it showed the same sort of "being stuck" symptom.

 

At this point I've just left it at this state. It turns on but it doesn't go through the post screen and nothing happens at all.

 

If you have any idea what is wrong then please let me know. Any help is appreciated.