Well, about the PSU, you don't actually need a 750w if you're going for a single gpu.
and no, overclocking your system will not make it consume 300w more lol.
from the article
Now the question gets asked often enough so I thought I would address it in a basic sense right here; What PSU do I need for my system?
Well most *high end single GPU systems will only need a 500-550w unit. Most *high end dual GPU systems will need a 750-850w unit. Most *High End Triple & Quad GPU setups will be in the 1000-1500w category.
Simple systems like an Athlon II x4 & HD5770 would run on a solid 400-450w PSU.
There's no need to over buy in the PSU category as half the time you'll be wasting away that nice 80+ Badge by running a unit below 20% load at idle.
*High End qualifies as: Core i7 920 @ 4.4Ghz, GTX 580 with high air overclocks, 2 HDD, 1 SSD, 1 ODD, 5 x 120mm fans.
If your case has good airflow (which it has) you won't need 40mm fans over your mosfets, they're not going to blow up.
And yes, the Silver Arrow will work no problem, 1155 boards use the same mounting system as 1156, which the silver arrow includes