many hw errors

[how-high]

I am getting many hw errors
100s a minute
why?

windows7 32bit

card MSI R7950 Twin Frozr 3GD5/OC BE G Radeon HD 7950 3GB 384-bit GDDR5 PCI Express

bat
setx GPU_MAX_ALLOC_PERCENT 100

setx GPU_USE_SYNC_OBJECTS 1

cgminer.exe --scrypt --auto-fan --temp-target 80 --temp-cutoff 90 -o x:3333 -u x.x -p x --shaders 80 --intensity 12 --worksize 256 -g 1

[how-high]

currently using this

cgminer --scrypt -w 256 --shaders 0 --intensity 12 -v 1 -g 1 --lookup-gap 2 --thread-concurrency 12000 --gpu-engine 1100 --gpu-memclock 1500 --gpu-memdiff 0 --gpu-powertune 20 --temp-cutoff 90 -o .com:3333 -u x.x -p x

and no errors
I cannot go any higher or the pc shutsdown
I think that's because of the psu being tot small