I've tried multiple PSU calculators and they all come out to around 700-800W with 90-100% load so I just assumed :p
I have a Core i7 Xeon overclocked to 4.5ghz, 6GB of RAM, 4x WD Green 1TBs, 2x SSDs, a PCI sound card, a USB 3.0 PCI-E host, about 5 USB ports in use, 8x 120mm fans, a water pump, and 3x CCFLs.

My old 1kw PSU died a month back while bitmining. I surely believe it was old age as it was a 4-5 year old Silverstone PSU, but I could never be quite sure due to the odd symptoms it was giving. So I just want to be safe before throwing another video card in :p