Anyone using AHCI ?

[jameson_uk]

When I installe d64bit Ultimate I changed the setting in the BIOS for my p5B mobo from IDE to AHCI. This worked fine and it all installed.

Now however performance is a little crap. I have tried to install the Intel 965 drivers but this did not do a lot. I am still getting IDE speeds (and worse) form the AHCI SATA ports...


Dont fancy a complete IDE reinstall so would be interested if anyone has any advice

[jameson_uk]

bump...

looking at it again.... anyone ????

[BUFF]

imo there is no real advantage to AHCI atm & as you have discoverd in some cases it actually loses performance ...

[jameson_uk]

imo there is no real advantage to AHCI atm & as you have discoverd in some cases it actually loses performance ...

But my mobo (Asus P5B) has either IDE or AHCI modes... So I either run as IDE or SATA.

[BUFF]

& IDE emulation is just as good.
AHCI allows you to use "advanced" features like NCQ & hotplugging but NCQ in an average desktop actually tends to lose performance & it's unlikely that you'll use hot plugging on the ICH8 ports.
The only other thing is that you will get faster burst transfer with AHCI but again it doesn't really have any effect & continuous transfer rates are the same.

[jameson_uk]

& IDE emulation is just as good
But does the IDE mode not run both the master and slave on the same channel at a max of 133Mhz ? I thought that the IDE mode simply ran the drives as IDE drives using a SATA interface ??

[BUFF]

No, it's an IDE emulation mode as a basic fallback.
Your drives are connected singly as SATA is point to point so there is no master/slave.
What do you think that the difference is between an IDE/PATA drive & an equivalent SATA drive? It's the interface, other than that the mechanics are the same & it's the mechanics that are the limiting factor - even a 10,000rpm Raptor won't break 100MB/s in continuous transfer & for your average 7,200rpm HDD it's typically 50-60MB/s, both within the limits of UDMA 5 let alone UDMA6 or SATA150.

[jameson_uk]

No, it's an IDE emulation mode as a basic fallback.
Your drives are connected singly as SATA is point to point so there is no master/slave.
In the manual it is very specific about the four ports being two master / slave sets in IDE mode. I also seem to recall running a test when I installed XP on IDE mode and it showed the drives as UDMA5.

Tempted to reinstall Vista now.....

[BUFF]

In the manual it is very specific about the four ports being two master / slave sets in IDE mode.
yes, it will show as that in the BIOS but each drive is connected directly & individually to a SATA port which is directly linked to the chipset (I'm assuming on the ICH8 not JMicron).

I also seem to recall running a test when I installed XP on IDE mode and it showed the drives as UDMA5.

quite possibly but it won't make a difference to the performance as the drives are physically incapable of stressing either interface in continuous transfer.