Every time I mine LTC I crash

[Draxus]

Hey all,

So I can mine BTC fine, but I want to mine LTC....but I always crash.

I have tried using multiple configurations in guiminer scrypt, reaper, and CGminer.

I have a sapphire 7950.  It came clocked like this:  
GPU Clock: 925
Memory Clock: 1250
VDDC: 1250

This card is in a PCI 2.0 X16 express slot
I have 8GB of Ram.

My best success is using the high usage in setting in Guiminer-scrypt....sometimes I can up to 3 hours before it crashes, at about 530khash/sec.

I am using the 13.4 Catalyst Drivers and I think the 2.8 SDK.

Any ideas?

EDIT: I never go over 75 celcius and my PSU is 730W