Update 8/9/2009: The latest Matrix drivers can be downloaded here. Although with Windows 7 RTM and these matrix drivers the LPMDSTATE is 1, I haven’t had a single freeze with my Raptor. Apparently Microsoft or Intel made changes to the drivers which don’t trigger the freeze, at least on my system.
I built my own PC a couple of years ago and used the Asus P5B-Deluxe motherboard, which I’ve been pretty happy with. I also wanted the fastest SATA hard drive possible, so I got a 10K RPM Western Digital 75GB Raptor. Unfortunately, in Windows Vista the SATA/AHCI drivers enable a special AHCI mode called Linked Power Mode (LPM) which is mostly used for laptops. The WD Raptors freak out if they get this command, and freeze up for 30 seconds or more. Meanwhile your system is unresponsive and I generally get quite frustrated. Other hard drives suffer from the same problem.
To my shock Windows 7 Beta 1 includes the same AHCI drivers as Vista RTM, which means my W7 was freezing on me (even in San Diego’s 80 degree weather) and performing quite badly. The solution with Vista is to install the latest Intel Matrix drivers and reboot.
My first attempt to install the Vista Intel Matrix drivers failed, with an error trying to copy the difxapi.dll. Running as administrator and Vista compatibility mode did not help either. After some additional research, I found a solution.
1. Download the latest Intel Matrix Storage Manager from my update notice above.
2. Run the installer as administrator. You should not get any errors.
3. Open Regedit and navigate to: HKLMSYSTEMCurrentControlSetServicesiaSTORParameters.
4. Change the LPMDSTATE value to zero for each port.
5. Reboot and enjoy a freeze-free system!
Let’s hope Microsoft and Intel ship drivers with Windows 7 RTM that don’t automatically enable LPM on desktop computers.