Could I have opinion of specialist about my Problem? I suspect a bug of the programm because that'is the only thing I had not check, someone can tell me if it's possible?

I offer on the other topic 30 Darkcoin Bounty to solve that problem, a nobody has a clue, but I get in touch with other that had the same problem.

Here is the facts:
I have 3 different R9 290, other people has 6 290 of other brand, after 10 minutes, the cards looses 10% of Hash.
That probelm happend only on R9 290 cars.
I'm on Bamt 1.6 from Bajawa, He is on windows 7, same problem.
All 290 on the same rig experiment the loss in the exact same second
if you put another card in the rigg that is not a 290, all the 290 had a loss, but not the other card
The cards are cold.
The problem happenedonly with sph-darkcoin miner, if I mine Litecoin, I'm stable.
I split the cards with 2 PSU, does not change a thing, cards crashed at the same time, no matter what psu they are plugged.
I change motherboard, does not change a thing.
I run 4 different sgminer, each one with one card activated: even I did launch them with a delay of 3 minutes, 10 minutes later, all the instance with a 290 had a 10% lossat the same time
I launched sgminer without a .conf: only intensity in the parameters: happened with I:18 and I:21 (0% rejected, cards should worked with high intensity)
Once I got the loss only a cold reboot can recover the missing hash. If I mine restart only the miner, it restart but is capped to 90% of max hashrate.

I'm getting out of hints. If the problem is in the programm, I shoud stop wasting my time. If it is not, I will keep investigate, even if I think I already get pretty far.
PS: as usual, english is not my first languagae, so if I offensed any-one, it was not intended.