3 7950 GPU 19 or 20 intensity

[powdabam]

If I run all 3 at 20 intensity I get driver errors and the 3rd gpu will never mine at all, the first 2 will.
If I run all 3 at 19 intensity it's perfectly fine, pulling in about 580 hash per card.  I'd rather have the 630 hash per card I get with the first 2.
If I run the first 2 at 20 intensity and the 3rd at 13 intensity I'm fine.

What does that sound like?

I have a 1000w Seasonic I paid $250 for.

I checked the Mobo voltages and the PCIe is getting 1.8v alone, that was stock.

Any ideas?
Thanks.

[computerparts]

50 intensity FTW!