Multi-GPU Setup

I have been given a HP DL585 G7 server, according to the HP Spec's, it has the following for PCI-Express

Expansion
# Technology Bus Width/Connector Width Form Factor Notes
1 PCI-Express x8 /x16 Full Length/Full Height
2 PCI-Express x8 /x16 Full Length/Full Height
3 PCI-Express x16 /x16 Full Length/Full Height
4 PCI-Express x8 /x16 Full Length/Full Height
5 PCI-Express x8 /x16 Full Length/Full Height
6 PCI-Express x16 /x16 Full Length/Full Height
7 PCI-Express x8 /x16 Full Length/Full Height
8 PCI-Express x8 /x16 Full Length/Full Height
9 PCI-Express x16 /x16 Full Length/Full Height
10 PCI-Express x8 /x16 Full Length/Full Height
11 PCI-Express x16 /x16 Full Length/Full Height

based on this, in theory would be possible to load it up 8-11 with video cards as an oclHashcat box? I read lots about the Tyan 77 motherboard, but a free server is free.. also I have 3 AMD/ATI R7 250x (non-reference boards), running in a desktop, so if this will work, I will update to the reference boards.

In this case if I an squeeze in 11 cards in the single box, are the 250/250x or cheaper cards and more of them, better than a single R9 card of some sort?

any feedback would be greatly appreciated.