Well I stumbled upon this thread after my pci-e riser cables stopped working. I just bought the case in mid-October too so just after a month and half. It stopped working.
I filed an RMA and I haven't heard back from Thermaltake. I wanted to know too if we're responsible on the shipping cost of returning the defective cable to them. Still waiting for a reply on that one as well. I tried phoning during their listed work hours but unsuccessful.
The case in itself is nice. But between the troubleshooting and waiting for support to contact you and the time the new cables gets shipped to you is very frustrating.
P.S. For the folks that bought the 3M brand. What size did you get 250mm or 500mm?