ADDITIONAL COMMENTS: This would be the first time I try to build a computer. I'm very worried it just won't work somehow or I'll end up missing wires or they won't be long enough or I short circuit something.
The build looks good, but it's too early to start planning the build if you're not going to purchase until August. This industry moves very fast. What we recommend today will most certainly change by August. I would come back about two weeks before your planned build date and ask for help picking components then.
I was actually planning on getting the Cooler Master 690 at first, but most of the reviews for the 5850 cards all say how big they were and recommended a full tower. This was actually why I'm so worried about the case, since I probably won't even use half the harddrive slots of a full tower case (and so much more expensive with the shipping fees) but I'm worried the 5850 cards won't fit in a mid tower.
Would a 650W PSU be able to support two 5850s in crossfire? I don't plan on getting two immediately but probably will sometime when their price drops a lot more. I always thought 750W seemed a bit high, but was worried about not having enough power for two graphic cards and end up having to buy another PSU. The PSU calculators gave conflicting results, with eXtreme PSU Calculator saying I only need 400+W and the Newegg calculator telling me 700+W.
And yeah it is a bit early I guess. I wanted to check if the prices of the stuff I'm planning to keep an eye on aren't incompatible with or bottlenecking each other. I'll probably have to bother you all again in a couple months :]
A 650W is big enough to support two 5850s. The problem is that few 650W PSUs have the required 4 PCIe connectors. This can be fixed by using adapters.
I generally go with a 750W for dual 5850s simply to have the extra connectors and have more room for overclocking and adding components.
The difference between those calculators is simple. The eXtreme tells you how much wattage is needed. Newegg tells you how much is recommened. Generally, you want to run everything at around 50% of the PSU's maximum load to maximize efficiency. So if you need 400W, you'd want to have a 700W+ unit.
The other difference is more of an observation. I think Newegg's calculator inflates the wattage for a couple of reasons. First, they don't assume you're buying a quality unit. If you buy a lower quailty PSU, the listed wattage is going to be higher than what the unit can actually do. Second, if they say you need a bigger unit, you'll spend more for a larger PSU. That means Newegg gets more money.