Can't help with why the OpenCL miner is giving you a lower hashrate directly (not familiar enough with it to know what -s does exactly), but have you checked the CGminer thread thread in the Mining | Software sub-forum? There are lots of switches and you can probably throttle that way? I know you can use -I for intensity, and can use "-I d" to keep it relatively low. I use this machine for work all day and am mining in the background and have good performance..
Wait, rereading your post, I see khash and then mhash. Are you mining BTC or LTC ? Mhash makes sense for BTC but khash only for LTC, unless that is one huge drop between CGMiner and OpenCL, which doesn't make much sense.
If you're solo-mining, BTC, even though it's for fun, I understand, you know the chances of actually hitting a block are about zero, so you're losing the opportunity to earn what you could in a pool in the interim, right?
Good luck.
Thanks for quick reply!
At the moment I'm not using the -s flag for the OpenCL since it is giving low rates. I'll look up the switches you're refering to. The only one I've used so far was intensity and when setting -I 1 it would still use 50% of the gpus performance when I'd like to throttle it even harder.
I'm mining BTC, I should've stated that in my initial post, my bad!
I am well aware of the chances being slim to none
I equate it to buying a lottery ticket (that only costs a few cents in electricity).