Under Linux, I have 6 Nvidia cards working. Not sure what is up with the Proliant G7 series. I have tried a DL360, DL380 and the DL580 and none of these will boot with more than 4 GPUs installed. Windows will lock up at loading screen.
Slap a USB stick with HiveOS on it and 6 get recognized easily.
I have a ML350P G8 that has taken 6 GPUs in windows easily.
Edit* Make that 9 1060s in one 580 in HiveOS.
Nice.
I am only going to be able to do 8 GTX 750's for now.
I only want to use the internal power and no breakout box/power supply. That means the three 10-pin to dual 6-pin cables could power six cards. The GTX 750's take up two card slots so each on them cover two PCIe slots. That does leave 7 slots left but with only 6 PCIe 6-pin power plugs adds to 8 cards. A similar solution and what I will do is put three GTX 750's in the internal PCIe slots that cover 6 PCIe slots leaving 5 PCIe slots free. I will use 5 risers for the external GTX 750's. That also adds up to eight.
If I want to do more than 8 then I will need to rewire the SAS power. I believe that is what you did. Can you provide details in how to do that?