ACHI and high CPU utilization in HD Tune

[brentsg]

System:

Intel Q9450 - stock speed
DFI LanParty LT X48-T2R
8GB DDR2
WD Raptor 150GB
NV 8800GTS-512
Vista Ultimate 64

I'm using the built in SATA controller and everything is configured for performance. Running the latest version of HD Tune.

Basically my issue is that if I enable AHCI in the BIOS, which has been enabled since the day the OS was installed, my CPU utilization is around 30%.

If I turn off AHCI in the BIOS, setting to IDE mode, the CPU utilization falls to 1.7% which seems correct.

Anyone have any insight? Thanks!

[Unexploded]

I'm running into the same thing, only worse. I've got a new x48-ds4 and not only does cpu jump through the roof when the drive is in use, just sitting in xp and not accessing the disk results in a constant 25-35% CPU utilization.

It appears to have something to do with the hardware interrupts. Kind of amusing as windows task's shows 99% idle, but with 35% cpu in use.

I've opened a ticket with the vendor, but if they don't have a fix, I'm definitely switching back to regular old sata. ACHI seems to work fine on my adaptec 1430sa (pseudo raid card), but I've had nothing but grief from ACHI on motherboards.

[SmokeRngs]

I don't have any trouble with high CPU use using AHCI in Vista64 even when copying gigabytes of data from one drive to another. However, HDTune shows my CPU usage as 96.5% on any drive I test. I'd say it's a bug with HDTune and nothing more.

http://www.hardfolding.com/ftag1.php/mem/207/1/1.png (http://www.hardfolding.com?go=38&tnum=33&id=207)