I recently bought two of these and both of their 3 to 4 pin adapters are faulty, the pass through on the 4 pin molex works fine but the 3 pin feed off the pass through doesnt work at all so it cant be used to power the fans.
I'm not bothered about this as I have plenty about and will probably be running these particular ones off the m/b anyway but this is just a heads up that you may wish to check a sample of stock as it seems unusual that both would be faulty.