Thank you for the responses!
Wongi: How do you look if the miner has many disconnects? Is it something like "0 shares detected".
Pontiacg5: I was trying to mine coins like DOGEcoin or CASINOcoin. My graphics card is the Gigabyte 7950, GV-R795WF3-3GD and in "https://litecoin.info/Mining_hardware_comparison" it states 729KH/s so I expect it to go above 650KH/s at the least. I use the default setting of GUIminer for 7950 at high usage that is:
Thread concurrency: 21712
Worksize: 256
Intensity: 20
Vectors: 1
GPU threads 2
The pool says I'm getting 150 KH/s when I should get 650KH/s at least. The pool I'm mining is DOGEhouse, but I have tried 5 others all with similar or worse results...
My PC physical location is in Spain (Europe)