Intel 82801 SATA AHCI controller: PIO or DMA?

[domi]

I have "Intel 82801GBM SATA AHCI Controller" listed under "IDE ATA/ATAPI controllers" in Device manager on my brand-new X60s running W2K SP4. The properties of that entry have an "Advanced Settings" tab, where I can pick up two possible values for Transfer mode (both for Device 0 and Device 1):

1) DMA if available
2) PIO only

Which one should I be using?

Thanks, Dominique

[christopher_wolf]

You should go with UDMA 5 under DMA.

PIO is a, very, old fallback option and is what some versions of Windows slip into when they detect I/O ops that either took too long or didn't complete for whatever reason.


Just to note; there is, what some would say, a bug in Windows where it would misinterpret I/O from an optical drive, which would be fine as far as the drive and the application using it went but would look like a crazed HDD to Windows. Hence, Windows would put all the drives in the system in PIO mode. Just in the event that you ever run into that problem.

There is an MS Database article about this that I posted somewhere here, do a search and you should find it.

[domi]

You should go with UDMA 5 under DMA.

Thanks for the explanation!
I have the following values for the time being:

Device 0:
Device type: Auto Detection (greyed out)
Transfer mode: DMA if available
Current Transfer Mode: PIO Mode

Device 1:
Device type: Auto Detection (not greyed out)
Transfer mode: DMA if available
Current Transfer Mode: Not Applicable

-> Why is PIO mode selected for Device 0 (which I believe is the HDD)? Is there anything I can do to convince my X60s to use DMA instead?

Thanks, Dominique

[f1reverb]

http://www.michna.com/kb/WxDMA.htm