Thanks for the update, Micro, was wondering what was up and am glad it's just machines, not backs.
I've been through that bit with the a_4 core, I presume, and I know this isn't your first episode either. If it's in fact the a_4 running one thread (one core) then it's electing to treat your machine as a single processor, that's what happened here. When you first went through this, we got you the 6.30 version which at that time got you a_3's instead of a_4's. Now very recently they've got new WU's which they're kind of forcing through and which require a_4. To run them however, you now need 6.34 which will then identify your machine properly and and d/l the LATEST a_4 which the new WU's require to run. Otherwise you sit there churning one core at 250 ppd. This at least is what happened here very recently on two and I think maybe three machines. The short answer for me was trash queue.dat, /work dir, core a_4, let it d/l a new w/u, do its thing, get itself the latest a_4 which then happily runs all 4 cores, and I don't know if you know this, it doesn't show until final points are rewarded, gives you a 10% bonus for all this folly.
I was right where you're at, ready to shut down the cpu side, but this worked. v7 btw fixes it too, but I like things slow and painful, lol.
Good going on the gpu fix.