Hi, guys. I have about £2500 to invest in litecoin rigs. One of the rigs is a replacement for my Sandy bridge rig and will be a gamer/miner, I will use it to game maybe 4 hours per month. The other rig is a cheap AMD platform. The haswell rig will run with my 7970, a 7950, and a 6950 I will purchase. The AMD build will run 4 7950s and a 6670 or super-budget card for displaying the screen w/o compromising the stability of the cards that are mining. Is it possible in cg miner or guiminer to only mine with four of the five Gpus I will have connected?
 
Here are the two builds, can they be improved?

Gamer/miner
I5-2500K
Gigabyte G1.Sniper2 (owned)
XFX 7970 (owned)
HIS or Sapphire 6950
Corsair HX1050 (owned)
Lian li T60
Optical drive, win7 h

Edit : updated build

The 7970 gives around 600kh/s, and the 6950 will get 400-450
Total hash rate : ~1000kh/s

AMD
Pentium G2010
Msi z77g65
4gb ram
5x sapphire vapor-x 7950
6670 (to power display)
Thermaltake 1475w psu
Optical drive, win7 hp
7950s will give around 600 each so 3000kh/s should be achievable. 6670 will give around 50kh/s should I decide to mine with it too.
Total hash rate : ~3000kh/s

Combined hash rate: ~ 4000kh/s

Thanks for your time!

Edit :builds updated