It's a i7-970 rig currently running W7 that occasionally picks up a A5. I have another i7-970 rig that has been down a couple of days while I've been trying to get the air out of a new water cooling installation.
I'm about ready to give up and put it back together.
I've set two rigs to run only A3 and another for A5. I've noticed several times when the A5 rig completes an A3 WU it picks up a 26xx WU but soon errors it and then loads another A3.