Help with ntune and 6600gt

[EmAn]

I have downloaded ntune for my 600gt (agp8x) and it said that it will overclock a nvidia card on any mobo... well when i try to up the clock (5-10 mhz) it does the auto test and fails... i have w/c on this so heat is NOT the issue does anybody know what the problem is???

my rig specs are in my sig

[redduc900]

The problem is nTune... uninstall it and install RivaTuner 2.01

http://downloads.guru3d.com/download.php?det=163

[EmAn]

alright i got that downloaded and installed... i restarted and it detected my clocks 500/900 and i adjusted it too 510/910 and applied it so does that mean it is overclocked now or do i have to restart?

and then what is a good video benchmark program?
or do i just have to game?

[EmAn]

ok i found out it is overclock (shows newbness)

http://i7.photobucket.com/albums/y293/eman8675309/vidcardoc.jpg

i am at 520/920
couple of questions...
how high should i be able to go *safely* without ramsinks
and
what should i be looking for as errors?

[EmAn]

now i am at 580/1000

i dont see any problems or "artifacts" (if i really know what to look for) how much high should i push it without ramsinks [not could]