I think you still need to power the HDD up with the Molex power connector. That one is different from the ones I used and yeah, it is going to slow down the HDD a TON. It is really hard to justify using them. After about a few months with them, I decided to just upgrade my HDD to SATAs. I would be careful and try every configuration of plugging things in, trying different cables. Other than that it doesnt look like you have any jumpers to messs with so I don't know what else to tell you. If that doesnt work then maybe cut your losses and get a new HDD/SDD.