870 Extreme3 R2.0/Dr.Debug "97"/R9 380 4GB

Hello, I would to ask if anyone can either point me to my error or provide a solution to my predicament.

I've been sporting a:
870 Extreme3 R2.0
AMD Phenom II 1090T 3,2
4 x 2GB RAM
Sapphire Radeon HD 6870

For a couple of years now and it has been blast.
But as I am preparing to trade my concrete horizon for the open sky (10NOV15)
I saw fit to upgrade my GPU and ordered a MSI R9 380 4GB.

Problem is, with it in place, I can't even enter the BIOS.
I've searched the web for a possible solution but am, quite frankly, at a loss.

I have:
- Flashed the BIOS, now packs Amercan Megatrends Inc. P1.80 12/6/2011
- Upgraded PSU to a Cooler Master GM G750M
- Plugged the card into friends PC, card is working great
- Booted PC with either, all previous drivers uninstalled, new drivers installed before boot (both with and without reboots whilst sporting the old card)

I believe both card and Mobo are in working order, are they just not compatible with each other, or am I missing something?

With kind regards,
Postinator42

Did not have the time till today to try.
That did the trick, thanks a lot!!!