Hello, 

Yes, it is doable. I am currently running 4x K80 in my server, which is essentially an 8x GPU setup. Runs great. You just need to note some parts as you set them up.

• Power breakout board: I think it is called a "power distribution" board, but check the parts for them. That board is located at the bottom of the motherboard. Lift up the MOBO, insert the power board in the extended slot (pretty easy), and insert the MOBO back.
  
  
• Power cable: Pin layout of this power board and the cable is basically an 8x PCIe power layout. PCIe in, PCIe out. (3 yellow power and black ground pairs, with 1 pair of ground). The problem is that, K80 uses a CPU power layout (4 yellow power and black ground pairs). You need an adapter or appropriate cable (Search for PCIe male to CPU or ATX male). We rewired the cables ourselves.
  https://i.stack.imgur.com/Spsgx.png
  
  
• From the specification of the board, each slot of the power breakout board can carry 300W (standard design is supposed to be 150W instead of 300W, so this is special for the T630), so it has no problem supporting 1 K80 each. So, one PCIe power slot would split into 2 CPU power slots. We have been running it fine for 2 years now, no problem. Be careful to pick a good power cable though. Thing is, you will read online that standard PCIe slots can only support 150W, and when running it, the T630 will give a notification of "power overloading". If you want to be safe, you can just do 2x K80.
  
  
  
• Install a stronger power supply. There are two slots for the PSU, dont care about the 2nd, they dont add to your system. You need a single strong PSU. The second is the spare PSU, which is there to ensure power redundancy.
  
  
• Fan array : With the GPU installed, the server won't run without the fan array (4-fan array in the middle of the chassis). Problem is, these fans are completely useless in cooling down the K80s. Therefore, you can just buy some jumpers or something to bypass it. Or just install the fan array per the requirement.
  
  
• Fan mod: K80s need a fan directly attached on one end of it, being a passive cooling solution. We just attach two server fans at the backend of the chassis, they cool the K80s down fine. Cover the slots where there are no GPU, leave only the ones with the GPU opened to increase pressure into them.