Mhash suddently drop ?

[18RATTT]

Hi guys,
im new here, was wondering if u can help me out a bit.
im mining btc using GUIminer in BTC guild pool.
one of my card is Geforce 660Ti (i know nvidia isnt best for mining but i would rather use it than its collecting dust), for the past few days its been constant getting 103 Mhash/sec.

however today after i installed (i dont know if this related) GPU-Z and MSI AfterBurner, i was trying to learn more about OCing,
the Mhash dropped to 60 Mhash/sec. and i didnt install anything else except those 2 apps

is it something bcos i install gpuz / afterburner or something else? please enlighten me.

thankyou for your time.

[altmine2]

Sometimes if you increase certain parameters the card's hashrate will decrease, this is normal. Just increase the parameter to just below the point where the hashrate drops.

[18RATTT]

i already reset everything back to normal. still nothing happen it sits in 60 Mhash