AHCI vs. Compatibility

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delaneybob · #1 Post by **delaneybob** » Sat Nov 03, 2007 4:15 pm

Hi,
I had a previous post where many helped me walk through a complete rebuild on a T61p with OEM XP. It's all done except one item.

I followed the Lenovo procedure exactly with a floppy and allowing XP to load the AHCI driver during installation of XP. My BIOS is in compatibility mode and when i swtich it to AHCI- I get BSOD.

Is it worth worrying about?

Thanks

#2 Post by **carbon_unit** » Sat Nov 03, 2007 4:49 pm

I don't think that AHCI provides much advantage at this point. Maybe in the future it will matter but right now it's no biggie. Do what works for you.

#3 Post by **jdhurst** » Sat Nov 03, 2007 5:26 pm

I have never tried it, but a quote from WiKi is as follows:

"Enabling AHCI in a system BIOS will cause a 0x7B Blue Screen of Death STOP error on installations of Windows XP where AHCI/RAID drivers for that system's chipset are not installed. Switching to AHCI mode requires installing new drivers before changing the BIOS settings."

FWIW .... JDH

DAH · #4 Post by **DAH** » Sat Nov 03, 2007 5:43 pm

delaneybob wrote:Hi,
I had a previous post where many helped me walk through a complete rebuild on a T61p with OEM XP. It's all done except one item.

I followed the Lenovo procedure exactly with a floppy and allowing XP to load the AHCI driver during installation of XP. My BIOS is in compatibility mode and when i swtich it to AHCI- I get BSOD.

Is it worth worrying about?

Thanks

When I have done this on my T60p I put the drive in AHCI mode before starting the rebuild of OEM XP I believe that is the key. IF the drive is not in AHCI mode I do not believe the drivers are loaded.

rxblitzrx · #5 Post by **rxblitzrx** » Sat Nov 03, 2007 8:01 pm

I just finished a fresh install of XP on my T61. Here are the steps:

1. Config -> SATA -> Change to Compatibility Mode

2. Install Windows

3. Unzip SATA Drivers (Intel Matrix Storage Manager)

4. Run the Install.cmd file

5. Reboot and change BIOS back to AICH Mode

delaneybob · #6 Post by **delaneybob** » Sat Nov 03, 2007 10:12 pm

Thanks!

#7 Post by **RonS** » Sun Nov 04, 2007 4:03 pm

I have benchmarked (several times) SATA in both AHCI and Compatibility mode, and have found no measurable difference in performance between the two.

#8 Post by **erik** » Sun Nov 04, 2007 4:25 pm

RonS wrote:I have benchmarked (several times) SATA in both AHCI and Compatibility mode, and have found no measurable difference in performance between the two.

same here. HD Tune gives the exact same results regardless of being in AHCI or compatibility mode.

rxblitzrx · #9 Post by **rxblitzrx** » Sun Nov 04, 2007 9:56 pm

erik wrote:
RonS wrote:I have benchmarked (several times) SATA in both AHCI and Compatibility mode, and have found no measurable difference in performance between the two.
same here. HD Tune gives the exact same results regardless of being in AHCI or compatibility mode.

Does that mean there's no difference between SATA and PATA or that the SATA controller doesn't help?

#10 Post by **erik** » Sun Nov 04, 2007 11:50 pm

rxblitzrx wrote:Does that mean there's no difference between SATA and PATA or that the SATA controller doesn't help?

it means that ATA bus speeds aren't fully utilized no matter what technology is used.

pibach · #11 Post by **pibach** » Tue Jan 01, 2008 8:17 am

erik wrote:
RonS wrote:I have benchmarked (several times) SATA in both AHCI and Compatibility mode, and have found no measurable difference in performance between the two.
same here. HD Tune gives the exact same results regardless of being in AHCI or compatibility mode.

This cannot benchmark the new queuing which should provide a significant performance improvement when multitasking with scattered disk accesses.

Also I expect some difference then in power consumption of the controller itself plus some improvements in head movements and disk spindown etc

www.lesswatts.org:

"SATA Aggressive Link Power Management
Several SATA controllers, that use the AHCI specification, have a feature called ALPM, which stands for Aggressive Link Power Management. ALPM is a technique where the SATA AHCI controller puts the SATA link to the disk into a very low power mode when there's no IO for awhile. The controller automatically puts the link back into active power state when there's real work to be done. This can save between 0.5 and 1.5 Watts of power."

AHCI vs. Compatibility

AHCI vs. Compatibility

Re: AHCI vs. Compatibility

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