how to set up cgminer properly?

hey guys i am very new to the mining scene and ive just got my first rig. its a four gpu rig all 7950's i have windows 7 64 bit as my os and have 12.8 and 2.7 drivers but for some reason i just can't grasp cgminer and how to work it i've tried guiminer scrypt and got things going but i was only able to get one gpu running. just so you guys have all the info my rig contains

psu: silverstone strider 1500W
mb:msi z77a-gd65
gpu: 4x power color hd 7950's
ram: 2x 4gb ddr3
hdd 500gb
4x 1x to 16x powered riser cables
os: windows 7 64 bit

im using cgminer 3.4.2

ive watched multiple cgminer how to videos but when i put in what they do obviously with my own details it doesnt want to work ive tried:

timeout /t 30
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer --scrypt -I 19 --thread-concurrency 21712 -o stratum+tcp://coinotron.com:3334 -u [USER] -p [PASS] and all i get is:

started cgminer 3.4.2
clDeviceNum returned error, no GPUs useable
no devices detected!
waiting on usb hotplug devices or press q to quit
probing for an alive pool
pool 0 difficulty changed to 256
network diff set to 74m
stratum from pool 0 detected new block

ive also tried:

cgminer.exe -o stratum+tcp://coinotron.com:3334 -u crazygypsy.1 -p 1 -I 1

but then my cgminer opens and windows says: cgminer.exe has stopped working

any help would be much appreciated