SATA 6GB speed not supported in Asus Rampage III Gene

I have Asus Rampage III gene motherboard with Intel Core i7 processor. It has support for sata 6GB/s technology. It has 2 sata III 6GB/s connector. I brought a new Seagate Barracuda 1 TB 7200RPM SATA 6Gb/s with 32MB Cache Internal hard Drive. I attach new hard drive with SATA 6GB/s connector but when boot the marvel controller it shows drive is connected to 3GB/s speed. I check in bios 6GB/s controller is also enabled and connected at AHCI mode. I update bios with latest version but cannot solve the problem. I disconnect the hard drive and connect it properly with SATA 6GB/s cable which is come along with motherboard but still same issue. I don’t understand is it problem with hard drive or marvel controller. Anyone knows how to solve this problem?

I also get this problem with ASUS Rampage III gene motherboard when I attach my new Western digital caviar 2TB SATA III 6GB/s black edition hard drive. I also try many things but still cannot solve problem. I think it is problem with Marvel and JMicron controller and I talk to ASUS about this problem but still cannot get any updates of marvel driver. Many of people got this problem and complain to ASUS still they cannot solve this problem. I hope they are working on this problem and give us the upgrades when problem is fixed.

I got same problem before a few days. My WD 1TB SATA 6GB/s hard drive shows 3GB/s speed in marvel controller. I think wrongly connected to 3GB/S port but I am wrong it is connected to 6GB/s port. I connect the hard drive with different sata cable and in different SATA 6GB/s port but cannot solve the problem. So, I talk to ASUS about this problem and they told me they never see that kind of problem in our motherboard and advice me to update the firmware of hard drive. So, I talk to the WD support center and got latest firmware and upgrade my hard drive firmware. Finally my hard drive is working with 6GB/s speed. Sometimes because of in-comp-ability that kind of problem is arrive. So, I think you have to try this solution and maybe it will works for you.

I got problem with my Hitachi 500GB 0F 15629 7200 RPM, 16mb cache hard drive. I have support of SATA III 6GB/s speed. I connect it with my ASUS rampage III motherboard at SATA III 6GB/s port but it shows it is connected with 3GB/s speed at marvel controller. I check connection, BIOS and everything but cannot solve the problem. I reconnect my hard drive with SATA III port and format it from computer management. Now I checked on marvel controller it shows the hard drive and which is connected at 6GB/s speed. In some cases that kind of problem is occurred because new hard drive is not formatted and we need to format it before use. I never see this issue again with my hard drive.