Calling all persuasive people!

3 sticks of 2GB would give 6GB and would work well in a triple channel system. Some intel based systems are triple channel (I think only some of the i7s are), whereas the rest and all AMD systems are dual channel.

I've given my suggestion for a specification, Suiseiseki has given his, which is no less valid than mine, however an AM3/bulldozer/discrete GPU system will cost more than the system I gave, and from mine you had roughly $125 left, so essentially you're still $175 under budget. It is certainly possible to build an AMD system along the lines of what Suiseiseki suggested for around $1,000, perhaps slightly less, quite possibly within your $850 budget, but I think you'd be hard pushed to get a decent gaming system using intel hardware within your budget.

 

well I can tell you what I have here, but its hardly top of the range. it does run skyrim well though.

AMD Athlon II x2 255 3.1Ghz dual core
MSI 770-C45 motherboard
16GB DDR3-1066 ram
ATI Radeon HD 5870 1GB
Asus Xonar D2 P/M 7.1 sound card
Intel Pro/1000CT NIC
3ware escalade 2 port SATA RAID controller
2x hitachi 320GB hard disks
2x samsung 1TB hard disks
1x western digital 500GB RE4
scythe mugen cooler
corsair TX850 PSU

dont remember what the case is