Need some advice upgrading GPU

Girlfriends Computer:
HP Pavilion HPE h9-1170 Phoenix Desktop: PC Specs Here

MOBO info here

AMD FX-8150
CORSAIR Vengeance 16GB (4 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
Eyefinity AMD Radeon HD 7770
Internal 600 Watt (100V-240V)
2x 2TB HDD
Windows 7 Ultimate SP1

I'm trying to upgrade the GPU in this system to at least 4GB. Any recommendations?
I'm having some trouble finding the supposed second 6pin connector the system specs claim is available i only found 1 connected to the Original GPU.
Also is it possible/or advisable to connect SATA-E to 4 pin Molex then to 6pin or 8pin? How would you connect a GPU that requires a second 6pin or an addition 8pin connection. Keep in mind she has 2HDDs so she has 1 SATA connection left.
BTW: I have been reading about HP negligence in upgrading BIOS. Is there a way to see if the BIOS will support a GPU?
If possible please make recommendations through New Egg.
Thanks in advance guys!
-Coen

 

OK how about this card? http://m.newegg.com/Product/index?itemnumber=14-127-884

Is it a mem upgrade or a downgrade from what she currently has? The stream processors might be smaller.
BTW: NVidia or Radeon doesn't matter.