These are not new cards or recent upgrades. I did not set up the BIOS myself. I have been running these cards on this PSU and with the same BIOS settings for the last 2+ years without ANY DIFFICULTIES. I have run WoW, SWTOR, Rift, AION, Skyrim, etc with NO ISSUES. The setup was built and tested by DigitalStorm, a company that specializes in gaming rigs. The problem ONLY happened when I installed and ran D3. I did not make any other hardware or software changes.
I don't remember the exact cost of the PSU in question as I purchased the machine at the end of 2009 but from a review of this particular model series of PSUs at xbitlabs: "Chieftec’s Super Series products are top class. They boast high quality of manufacture, excellent electrical parameters, a sufficient selection of cables, and quiet operation even at high loads." (http://www.xbitlabs.com/articles/cases/display/chieftec-psu-roundup_13.html) That doesn't sound like a crappy choice to me.
Also if you read my most recent posts, you would know that I have tested this now with only a single card in the primary PCIe slot so there should be no "load imbalance" or whatever you are trying to imply here.
According to this review: (http://www.guru3d.com/article/geforce-gtx-295-review-bfg/5)
GeForce GTX 295
A GeForce GTX 295 requires you to have a 700 Watt power supply unit at minimum if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 50 Amps available on the 12 volts rails.
GeForce GTX 295 Quad SLI
A second GeForce GTX 295 requires you to add another 300 Watts. You need a 1000 Watt power supply unit if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 70 Amps available on the 12 volts rails.
I have a 1200W supply (1200>1000) and two rails with 25A and two rails with 20A. I'm pretty sure that totals to 90A, which should be plenty to run both cards.
Now it is possible that there is something that has decided to fail in the power supply, but I find it hard to believe that coincidence with so many others having the same issue with D3 + GTX 295s. Still, I will see about testing the supply to make sure it hasn't gone on the blink. =P