I run them (T7500s). You can fit 3x GPUs directly on the board or use risers for better heat dissipation. There are 2x 6pin and 1x 8pin GPU power cables inside in the 1100w silver 80+ PSU.

Also, I run a pair of X5670s (and some x5680s in one) and when running the -t 18 switch on cpuminer and pick up 200h/s on ETN and keep the processors below 80% (extra $1+ a day). Ive tried using risers and breakout boards to get more than 3 GPUS and you cannot. I was able to get 4 for a short while, but it was too unstable and 5 would lock the system up the minute the miner was launched. I tried both the cheap 4 lane cards and the expensive 8 lane ones. Even thought the chipset has 40 PCIE lanes and the board has 36 usable, I can only get 3 cards to run reliably. I have used RX560, RX570/580 & 1070ti's in these.

I started with T7500's as they are a great computer for the money and have a bunch of them, but have quickly moved to new mining builds using dedicated mining boards. The T7500 with XEONS will take on modern i7s anyday if gaming or cad is your deal, but as a mining rig its a little limited for my taste... Mostly because they are server size boxes. I can fit 38 GPUs on a rolling 3" wide bakers rack but only 5 (ie 15gpus) of T7500s.