I dont have nforce but SiS. Tried SiS drivers and MS std drivers. An LG on the same cable works fine. Also tried the drives separately as master, and swapped them on the cable, master/slave. Disconnected other power consumers. Improved ventilation. Changed IDE cable on 2nd IDE.
The LG always works fine, the BenQ always gives problems. And now it seems to have ruined a DVD-RW. Yuck.
EDIT: It worked fine at first (some hours). Now, 24h later, it starts to behave strange again. And no, it is not my power supply. Have tried 2 and also both with minimal number of consumers plugged in. BenQ gets much warmer in idle than LG, too.
EDIT 2: Well this is the 2nd one they sent me. If I get to the third, I will post here about it for sure. But I would guess the dealer will refund me the money and not send me a 3rd drive - when I send the drive back, it is nearly 13 Euros for the dealer, he sends me a new one, 6 for him, so about 19 for each swap. One swap already done for a drive costing 58 ... 58-19=39, one more swap=20. I think he would not want to do that.