Good gaming build under $800?

get an i5 3450
a 7870
an asrock b75 motheroard
2x4gb ram
a 600w psu
1tb disc drive
windows 7 and a dvd drive
that should keep you under 800.

I5: http://www.newegg.ca/Product/Product.aspx?Item=N82E1681...
Amd 7870
Gtx 580: http://www.newegg.ca/Product/Product.aspx?Item=N82E1681...
4gb ram: http://www.newegg.ca/Product/Product.aspx?Item=N82E1682...
Case: http://www.newegg.ca/Product/Product.aspx?Item=N82E1681...
Motherboard: z77 mobo any will do. http://www.newegg.ca/Product/Product.aspx?Item=N82E1681...
Hard drive: http://www.newegg.ca/Product/Product.aspx?Item=N82E1682...
Cpu cooler: http://www.newegg.ca/Product/Product.aspx?Item=N82E1683...

Oh and dvd drive my bad and any 500w will be good

Don't get this. The 580 is overpriced. Get a 7870 or 7950 instead, they are more powerful and cheaper. Don't go with anything he had. My build will be more powerful and less expensive.

I have a 7950 and its $350   my build is very well

yes but the 7950 is about 30% stronger and the 7870 is about 23-26% stronger than the 580 and both are less expensive. the 7950 is about $300.

I think you have no idea what youre talking about. Last time i checked bf3 favors nvidia

bf3 used to favor nvidia. Now it is about equal because they have made catalyst drivers 12.11. Also even if this were true that wouldn't mean it is overall more powerful. But with 12.11 drivers the 7970's performance increased something like 20fps higher than its previous drivers. Which puts it above the 680. Also here is a benchmark of the 7950 and 7970 right when they came out vs 580. They still won
http://www.tomshardware.com/reviews/radeon-hd-7950-over...