Can GTX 980 Ti SLI and Intel 750 PCIe NVMe SSD be powered by my 685 watt power supply?

I have the following components:

Dell Precision tower 5810 with Xeon E5-1620 v3 (4C, 3.5GHz, Turbo, HT, 10M, 140W).
Intel 750 PCIe 400 GB SSD

Question:

I'm considering purchasing the new GTX 980 Ti. I know that my setup can power one of the cards, but could it handle two in SLI with only a 685 watt power supply? Keep in mind that those cards have a TDP of 250 watts each.