I just installed a new Zalman VF900CU and my temps dropped to 33 Celsius idle and 40 load, compared to 50 idle and 80+ load and now I am looking to Overclock.
 
I have followed the instructions on the sticky on how to OC but how many artifacts is too many or do you not want any at all?

Also when I use ATI tools and use the sliders nothing happens it freezes for a second and then stops something isnt letting me change the clocks on my card help plz

Wow I am stupid forgot to plug in the 6 pin pic-e power connector now im running a 645/745 OC on my 7950GT from stock 565/715

So you fixed your problem?
 
To answer your first question, it's okay to have some artifacts, it will usually never show up in games.

I fixed that problem but now how do I save an Overclock so it's there everytime I start my computer and when I get above 745 Mem clock my screen starts shaking and I can't see anything how do i get around that because my card is running reallly cool but I can't oc nemore because of it.

well you can save your setting in BIOS  by using Nibitor and nvFlash TO FLASH YOUR BIOS TO DESIRE CLOCK SPEED.
but always remember to save a back up copy of your original BIOS though.

You have to enable a setting. Look around in the options. But if your screen start shaking because of the mem clock, it's probably too high and is causing issues.

make sure you monitor the temp closely as speed climbs up.