CPU takes hashes away from GPU

[kervinmarketing]

Hi,

I'm running some antiquated hardware and when I run the GPU by itself, it hashes about 200KH/s. The CPU by itself hashes about 40KH/s. Obviously neither of these is impressive, and I'm just stockpiling some worthless coins on ScryptGuild. When I run the GPU and CPU together, the GPU drops to ~160KH/s and the CPU remains at 40KH/s. How can I prevent the GPU from mining slower when the CPU is also mining?

I'm running the following:
- Windows 7
- AMD Radeon HD6750 on CGMiner 3.7.2 and Catalyst 13.12
- AMD Phenom II X6 1090T on Pooler CPU Miner 2.3.3

[Wipeout2097]

You must leave one of the CPU threads free for controlling GPU mining.

Use -t 5 on the CPU miner command line, or better yet, use the commandline
start /idle minerd -t 5 ...
That also lowers priority of intensive threads

Scrypt mining with the CPU is pointless, though.

[SpeedDemon13]

I usually leave 2 threads free, just for overhead and just in case other system resources need the extra thread.

[kervinmarketing]

Awesome, thanks guys. Yes I realize it is pointless, just trying to understand as much as possible.