Summary: This computer is an HP, so upgrades are limited or not possible. This is a flaw with the HP design, and has nothing to do with the seller. The HP Compaq Elite 8100 CMT has a 320W Power Supply. The Graphics Processing Unit (GPU) used on this machine is a 512MB Nvidia GPU.
Summary: I had problems with the first on shipped. I called the company that refurbished it and we went through some steps to get it to work but ended up shipping back to Overstock. The second one had the same problem ended up calling that same company again and they wouldn't return my calls.
Summary: Nice big tower, with first gen i7 running Windows 7 Pro. No Windows 8 thanks. What a weird OS. What were they thinking? Oh, I guess they weren't. Nah, you guys will never catch Mac, so give it up. W7 is fine, so stay with it. The support from the vendor has been great.