Tutorial : How to switch from IRRT to AHCI mode - E6400/E6500 (Vista)

If I plan on wiping my drive to install vista x64, is there any reason to go through these steps or should I just make the bios change and then boot from the install CD?

 

No, this is just for existing installs where you don't want to go through the hassle of reinstalling everything all over again.

In your case just change SATA mode from IRRT to AHCI in the bios before installing Vista.

 

I just did the change over to AHCI and now I find that my latency spikes are actually much higher and much more frequent. So, where I had acceptable (but not perfect) audio performance before. I now have totally unacceptable audio performance.

EDIT: I'm not sure what happened, but after about five minutes, the spikes all dropped down into the yellow range and audio playback smoothed out. This is the same performance that I had before the fix, so at least I haven't gone backwards, but I'm not really seeing any improvements by switching to AHCI (I was already using the A02 driver).

EDIT2: OK. I just rebooted and started DPC as soon as I got to the desktop. For the first two minutes I was getting latency spikes over 16000. Then everything settled down to peaks around 1200 (still in the yellow range and higher than I would like). I wonder what Vista is doing right after bootup that causes the spikes?

 

AWESOME TUTORIAL!
Really good work.

/KimmoK

 

Sorry but it's not possible that latency increased by only going to AHCI from IRRT. I have 22 systems here as a basis for this conclusion, so I'm quite certain of this. IRRT continually polls the ports for raid events, AHCI doesn't.
What version of the Intel Matrix drivers did you install again when switching to AHCI ? Hopefully not 8.7.

But from reading your edit updates, I gather that now latency is ok ?

You can't base DPC latency on the first two minutes when Vista boots because it's doing many things that cause heavy drive activity. Indexing, Windows update, prefetch balancing and loading services are just some examples.

 

Is this applicable to XP?
I have Dell factory installed XP image now. Any registry modifications needed?

 

MiB - nice work!
After going from IRRT to ACPI, why wouldn't one use the Dell A04 (8.7) Matrix drivers?
Is there a particular reason you suggest the A02 (8.1) drivers?

 

Is the SSD you have the same one that Dell offers as their "Ultra Performance" option?

Thanks,
Harvey

 

Thanks.

Actualy, the ones linked in the tutorial are the stable 8.2.2.1001 drivers.
Intel's 8.7 drivers are buggy, but you're welcome to try them. You can always revert back to 8.2 if you like.

 

I have the same question--I have XP, factory install, IRRT. Trying to switch to AHCI causes BSOD; I'd like to fix that, so I can try AHCI and see if it fixes DCP spikes.