It really depends on what specs you are going to be running.....
Are you planning on overclocking? Crossfire? SLI?
If you are, the i would go with the Huntkey X7 900W, as you get the extra 50W As "Cushioning", And it looks like an overall better PSU.
Well, i am running a Radeon HD 5970 (Basically XFire 5850) and i have a Phenom II X6 1090T OC @ 4GHz, And my PSU is only 850W (HX850W Corsair). I personally think that your right about getting a new PSU. So i would get the 850W, But your GPU's pull quite a bit of power so if in the future if you plan to chuck another one in then your just gonna have to upgrade again to the 900W
I would just go with the 850W, because i'm basically running the same GPU's as you and i have overclocked mine, and it works great.
Good to see another person with good taste in CPU's
What is your budget for the PSU and where will you be buying from? As maybe could get a more reputiable brand of PSu for you, but if its only between these 2, i'd opt for the Huntkey as i had the 650W (rocketfish or something, was a rebranded one) and it worked fine for my system (still is in another system i built)
@reccy actually im in japan so psus tend to cost a lot here..the 850w corsair modular goes for around 18000 yen or around $170..actually didnt want to spend any on the psu..hahaha..but i guess i have to..so my budget is arpund $150..but as i said im in japan so not all psus are available here..
the scythe is a good one ive heard of it they are popular in fans and cooling as well but i havent heard of huntkey but if i were you i would definaitely go with the scythe and its effficiency is 80-silver thats a good sign and that it has been tested rigoursly under all conditions.. and so i hihly recommend the scythe if you can do in for the crosair as thats a time-tested awesum brand!!