Hi, I think I was bidding on that Titan you bought
this is what I would do, -- replace the thermal paste, clean the heatsink & pcb with some 99.9% isopropyl alcohol & brush, blow it out real good, and replace the fans with noctura highspeed fans , then let them run for awhile. With the noctura fans & a clean heat sink you may not need any more cooling (dcdc heatsinks)
http://www.amazon.com/Arctic-Silver-High-Density-Polysynthetic-AS5-12GRFB/dp/B001JYVFLY?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage
http://www.amazon.com/Bearing-Cooling-NF-A14-iPPC-3000-PWM/dp/B00KFCRF1A?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage
http://www.amazon.com/MG-Chemicals-Isopropyl-Alcohol-Cleaner/dp/B005DNQX3C?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage
http://www.amazon.com/MG-Chemicals-852-Non-Abrasive-Cleaning/dp/B004SPCXYO?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage
good luck
TXSteve, Thanks for the links. The Titan arrived today... Let's just say you should be glad you didn't buy it... One dead cube that won't power up at all. On cube with 2 bad dies and is as stable as a one legged chair. And there appears to be some issues with the power supplies that I haven't quite figured out. I can only get one power supply to run one cube at a time. You try connecting any other PCI-E cables to the power supply and you hear it click and then it won't startup. Not sure if these are just drawing too much power, or the PSU's are setup to handle it. Only the 8pin to 6 pin cables from the PSU seem capable of running a single cube with the y cable. The PSU's are Corsair CS750M's and the rig came with 2 of them. He also threw in a 1200w HP power supply with some PCI-E cables, but something is not right about those cables. As soon as you plug them in the power supplies won't run. None of the 3 power supplies will run with those cables attached. Not sure if it is me, or if there is something wrong with the cables.
I have been sitting here all night trying to tune and stabilize the remaining running cubes and this one with the 2 bad dies just isn't going to cut it. I have dialed back to 200mhz and I am still having them lock and disappear from the Advanced page. At this point I have sent a couple of message on eBay to the seller and no reply yet. I am about to start the return process on eBay. This guy said the rig hashed at 223mh.... Well not with one completely dead cube and one that will hardly stay alive... So I am a little frustrated to say the least.
I would love you guys feedback on this. Thanks!
750w is pretty small, it might only reliably run 1 cube. You might want to try troubleshooting with a known good PSU & good cables. The one completely dead cube might be a bad capacitor(I had 2 like that). I'd check the thermal paste(Bad paste can cause a flaky cube) and clean them , you can wait to replace the fans to see if they run hot.
I've had mixed results returning stuff to ebay. If you paid with a credit card then threaten to do a cc chargeback(it's always worked for me). If you used the default charge to bank acct it's a lot harder.
good luck