# AHCI setup for SSDs



## Frag_Maniac (Dec 13, 2012)

I have a Plextor M5P 128GB I bought recently and followed this guide to set it up, which I was told on the Plextor forum is a pretty good one that covers all the bases.

I enabled the SATA storage type as AHCI before installing the OS, but my drive is showing as [*IDE*: SO PLEXTOR PX] in the storage boot order of the BIOS. 

I found another setting in the BIOS you can adjust to AHCI that I wasn't aware of, the SATA 3 controller. Setting it to AHCI after the OS install however results in the drive still showing as IDE.

According to Plextor, the drive can be run as IDE or AHCI, but should run faster as AHCI. I was kinda surprised the Plextor tech didn't know whether the SATA 3 controller has to be set to AHCI before installing the OS for the drive to show as AHCI in the BIOS, but he's going to get back to me on that.

Prior to getting a SATA 3 drive, in preparation I read about how to change registry settings if you want to just change the SATA storage type to AHCI in the BIOS vs re-install the OS. That worked no problem, but this is a fresh install.

*Does anyone know of a way to change registry settings to AHCI specifically for the SATA 3 controller?*

I've read a fair bit about the onboard Marvell 9128 SATA 3 controller my MB has. A lot of people don't even use it and just run SATA 2. In testing however I get much faster read speeds on it than SATA 2, about 390 vs 270. The write goes up slightly on SATA 2 from 240 to 256, but overall, SATA 3 has been much faster. I want to see if it can run even faster if I can get the drive to show as AHCI in the BIOS though.


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## Disparia (Dec 13, 2012)

Which motherboard do you have? While it's a common controller, perhaps there is a known issue with your specific motherboard. If not, it still helps us to know what you are using.


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## Tatty_One (Dec 13, 2012)

I actually installed my SSD and then configured to AHCI in Bios without a fresh install of windows.... worked a treat, on startup windows detected the drive as "new" hardware, loaded some drivers, requested a re-boot and all was done, checked Device Manager and it was showing correctly.

I am wondering if your Windows AHCI drivers are installed correctly...... do you have something looking like this in Device Manager............


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## Frag_Maniac (Dec 13, 2012)

My MB is the ASUS P6X58D-E. As far as I know the main issue is that the Marvell SATA 3 controller is just not nearly as fast as the Intel SATA 3 controllers that are built into MBs now. Some have said they can cause lockups though.

Yeah I've installed the OS then switched to AHCI afterward too tatty, but it takes a registry tweak to do it properly. That was not necessary in this case however because the BIOS was already set to AHCI for SATA storage type before installing the OS.

Device Manager is not a thorough way of knowing if your SATA storage setting is adjusted to AHCI properly. You need to look at the msahci registry value for it and it has to be set to 0. My Device Manager does show an AHCI driver like yours, but only one instance.

Since making this thread, someone on the Plextor forum got back to me and said to DL and launch the AS SSD bench tool to see how it designates the drive. On the Marvell SATA 3 port it shows as SCSI. On the Intel SATA 2 port it shows as ATA.

This makes me wonder if the Marvell controller actually acts as a SCSI adapter of sorts. Anyways, I've recently compared speeds again, this time at 4k to see which has better sysem performance. I get same read speed on SATA 2 & 3, but write speed is 70 MB/s on SATA 2 and only 59 MB/s on SATA 3.

So for now I'm running it on the SATA 2 port. If that Marvell SATA 3 controller IS acting as a SCSI adapter, I'm hoping this way there will also be less lockups in games.


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## Maban (Dec 14, 2012)

I've only half read this thread so excuse me if I missed something. Have you set specifically the Marvell controller to AHCI in the BIOS? Advanced -> Onboard Devices Configuration -> Marvell 9128 Controller


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## Frag_Maniac (Dec 14, 2012)

Maban said:


> I've only half read this thread so excuse me if I missed something. Have you set specifically the Marvell controller to AHCI in the BIOS? Advanced -> Onboard Devices Configuration -> Marvell 9128 Controller



Yes I have, but since I was unaware of that setting before the OS install, I adjusted it after the OS install. I'm not sure that matters though. I've read some chat about people trying to get their SATA 3 controllers working as fast as possible and one actually recommended setting the controller to AHCI only AFTER it's driver is installed.

Then it dawned on me, since the SATA 3 controller is technically an addon part (even though built-in to the MB), it has it's own separate driver vs one from a BIOS and/or Windows database. So theoretically it shouldn't matter if it's set to AHCI after the OS install. Does that make sense?

I just don't get why my BIOS labels it as "IDE". Then again, part of that thread I was reading about people tweaking their SATA 3 controllers indicated Windows and/or some MB BIOS can sometimes mislabel drives. If so, I would think there's even more chance of it with a 3rd party controller, vs one made by the chipset vendor, which is Intel in this case.


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