The Hx 850w is $150, modular and got rated 9.5¬/10 on jonnyguru http://www.newegg.com/Product/Product.aspx?Item=N82E168...
^thats the hcg900w, $110 900w, non modular and got rated 9.5/10 on jonnyguru
jonnygurus pretty much the best reviewer for psu's so . Your choice, pay $40 more (even more price difference after taxes..) for a modular psu that got the same rating, or the cheaper option that is rated at 50w higher.
50w doesnt really matter. And yes, it is significantly cheaper. However, it's the modularity that matters. It cuts down on clutter, and that is very important to good airflow, which is important to 480's.
So will this 850w PSU have enough wattage for Overclocking both GPU's and the CPU? How much extra wattage is left for the system?
I'm very anxious when it comes to spending this much money on something that could potentially destroy my system.
Ehh, you're looking at a max of about 500w for the gpu's, probably 100~125 for the CPU, 50w for the rest. That should run your PSU at 600~650w or 70% efficiency. It might not be a bad idea to step up to a kilowatt if you want. However, 850w should be sufficient. Especially that Corsair.