two PCI Express™slots (1 x 4 lane and 1 x 8 lane)
so yes you may need riser cables to go from the x4 and x8 slot to a x16 slot - something like
thisthe issue would be that 7950's need two 6 pin power connectors i would imagine they don't come on Server Power Supplies
you could get adapters like
these but im not sure of the power connectors in the servers could even be sata ones
the biggest problem would be the server is rack mounted and with a 7950 you wouldn't be able to close the lid
although with riser cables you could cut a hole in the lid and run the graphics cards outside?
you could probably get a old second hand P4 motherboard with heaps of PCIEx1 slots grab a beastly power supply for around 200 mb+cpu($50) PSU(150)
use a usb to boot from so no HDD needed folow
cryptobadgers tutorial for linux
stick it all in a
milk crate