From: EGK on
Has anyone else had a problem utlizing AHCI in their bios? I'm using the
Asus p5b motherboard running windows7 64bit and thought I'd turn on the AHCI
in the bios rather than running my drives in IDE mode. I have two sata hard
drives and an sata dvd burner.

I'm able to switch back and forth between modes with a registry file to
enable AHCI support and deleting the drive controllers in device manager so
they re-detect when making the change. All drives show as running in ultra
DMA5 when I do this. My problem is when I shut the machine off in AHCI
mode the next time I turn it on, device manager is showing the hard drives
running in mutl-word DMA 2 instead. IDE settings cause no such problems.

I could just leave it on IDE since there doesn't seem to be much, if any
performance benefit from AHCI and I don't need the hot swap capability.
But... I like to get things to work the way they're supposed to.

So, has anyone else run in to a problem like this? I find lots of
references to the same problem on web forums but no actual fixes. The only
thing I saw that might be accurate was it's just windows mis-reporting the
DMA speed.
From: William on


"EGK" <me(a)privacy.net> wrote in message
news:apu6n5hdcsjfg9tgvlb1a8u8n01p1rm7e8(a)4ax.com...
> Has anyone else had a problem utlizing AHCI in their bios? I'm using the
> Asus p5b motherboard running windows7 64bit and thought I'd turn on the
> AHCI
> in the bios rather than running my drives in IDE mode. I have two sata
> hard
> drives and an sata dvd burner.
>
> I'm able to switch back and forth between modes with a registry file to
> enable AHCI support and deleting the drive controllers in device manager
> so
> they re-detect when making the change. All drives show as running in
> ultra
> DMA5 when I do this. My problem is when I shut the machine off in AHCI
> mode the next time I turn it on, device manager is showing the hard drives
> running in mutl-word DMA 2 instead. IDE settings cause no such
> problems.
>
> I could just leave it on IDE since there doesn't seem to be much, if any
> performance benefit from AHCI and I don't need the hot swap capability.
> But... I like to get things to work the way they're supposed to.
>
> So, has anyone else run in to a problem like this? I find lots of
> references to the same problem on web forums but no actual fixes. The
> only
> thing I saw that might be accurate was it's just windows mis-reporting the
> DMA speed.

I tried to run AHCI mode after obtaining an external enclosure that had
E-SATA - USB interface with a 1.5tb hd inside, a Roswill RX-358-S with a
Samsung 1.5TB Green HD. I wanted to run hot swapping capability on the
system. After turning it on in BIOS, I lost my boot sequence and had to
move the hard drives around - again. Then Win7 Ultimate 64bit failed to
boot. Win7 went into a repair mode and rolled back to a previous restore
point. Still no boot, and it wanted to do another rollback. I stopped this
and went back into BIOS and moved the HD system back to IDE and Win 7 booted
as usual.

I gave up and have been waiting to see what other people have to say on the
subject. You are the first to post on this subject on this news forum. On
ASUS' forum, P7P55D EVO web site, no one has given me an answer to this
question. I figured in time their will be enough interest in this subject
that MS will come up with a fix or something.

System: ASUS P7P55D EVO mobo, Intel Core i7 650 cpu, 8gig Corsair Dominator
DDR3 1600 ram, 750wt Corsair psu, WD VelociRaptor 300 gb boot drive, 2-
1.5tb Samsung green hds data drives, MS Windows Ultimate 64bit os, ATI
HD4870 graphics, Hauppauge HVR-1800 tuner card, lots more.

William



From: Rob on

"William" <nospam(a)pacifier.com> wrote in message
news:zrWdnQfiPpS-LenWnZ2dnUVZ_s6dnZ2d(a)posted.palinacquisition...
>
>
> "EGK" <me(a)privacy.net> wrote in message
> news:apu6n5hdcsjfg9tgvlb1a8u8n01p1rm7e8(a)4ax.com...
>> Has anyone else had a problem utlizing AHCI in their bios? I'm using the
>> Asus p5b motherboard running windows7 64bit and thought I'd turn on the
>> AHCI
>> in the bios rather than running my drives in IDE mode. I have two sata
>> hard
>> drives and an sata dvd burner.
>>
>> I'm able to switch back and forth between modes with a registry file to
>> enable AHCI support and deleting the drive controllers in device manager
>> so
>> they re-detect when making the change. All drives show as running in
>> ultra
>> DMA5 when I do this. My problem is when I shut the machine off in AHCI
>> mode the next time I turn it on, device manager is showing the hard
>> drives
>> running in mutl-word DMA 2 instead. IDE settings cause no such
>> problems.
>>
>> I could just leave it on IDE since there doesn't seem to be much, if any
>> performance benefit from AHCI and I don't need the hot swap capability.
>> But... I like to get things to work the way they're supposed to.
>>
>> So, has anyone else run in to a problem like this? I find lots of
>> references to the same problem on web forums but no actual fixes. The
>> only
>> thing I saw that might be accurate was it's just windows mis-reporting
>> the
>> DMA speed.
>
> I tried to run AHCI mode after obtaining an external enclosure that had
> E-SATA - USB interface with a 1.5tb hd inside, a Roswill RX-358-S with a
> Samsung 1.5TB Green HD. I wanted to run hot swapping capability on the
> system. After turning it on in BIOS, I lost my boot sequence and had to
> move the hard drives around - again. Then Win7 Ultimate 64bit failed to
> boot. Win7 went into a repair mode and rolled back to a previous restore
> point. Still no boot, and it wanted to do another rollback. I stopped
> this and went back into BIOS and moved the HD system back to IDE and Win 7
> booted as usual.
>
> I gave up and have been waiting to see what other people have to say on
> the subject. You are the first to post on this subject on this news
> forum. On ASUS' forum, P7P55D EVO web site, no one has given me an answer
> to this question. I figured in time their will be enough interest in this
> subject that MS will come up with a fix or something.
>
> System: ASUS P7P55D EVO mobo, Intel Core i7 650 cpu, 8gig Corsair
> Dominator DDR3 1600 ram, 750wt Corsair psu, WD VelociRaptor 300 gb boot
> drive, 2- 1.5tb Samsung green hds data drives, MS Windows Ultimate 64bit
> os, ATI HD4870 graphics, Hauppauge HVR-1800 tuner card, lots more.

In general, one should choose AHCI or IDE before installation.
While it is sometimes possible to change it (eg by a repair install
in XP) in an installed system, there is no guarantee that anything
other than a fresh install will work properly. AHCI enables NCQ
support as well as hot-plug capability.
OP: If the SATA drives benchmark at expected speeds after the
device removal/redetection and correct AHCI drivers, I personally
wouldn't worry about the reported DMA parameters, as these
could well be bogus.
--
Rob



From: EGK on
On Fri, 12 Feb 2010 16:13:38 -0000, "Rob" <noone(a)nowhere.noway.com> wrote:


>> "EGK" <me(a)privacy.net> wrote in message
>>> My problem is when I shut the machine off in AHCI
>>> mode the next time I turn it on, device manager is showing the hard
>>> drives
>>> running in mutl-word DMA 2 instead. IDE settings cause no such
>>> problems.
>>>
>>> I could just leave it on IDE since there doesn't seem to be much, if any
>>> performance benefit from AHCI and I don't need the hot swap capability.
>>> But... I like to get things to work the way they're supposed to.
>>>
>>> So, has anyone else run in to a problem like this? I find lots of
>>> references to the same problem on web forums but no actual fixes. The
>>> only
>>> thing I saw that might be accurate was it's just windows mis-reporting
>>> the
>>> DMA speed.

>In general, one should choose AHCI or IDE before installation.
>While it is sometimes possible to change it (eg by a repair install
>in XP) in an installed system, there is no guarantee that anything
>other than a fresh install will work properly. AHCI enables NCQ
>support as well as hot-plug capability.

Windows 7 should definitely be able to make the change on the fly since it
has drivers included for AHCI. It's just one simple registry change to
enable them. XP you need to turn AHCI on before a clean install because
you need to load external drivers.

>OP: If the SATA drives benchmark at expected speeds after the
>device removal/redetection and correct AHCI drivers, I personally
>wouldn't worry about the reported DMA parameters, as these
>could well be bogus.

I think that's what's happening but wondered if anyone else was seeing the
same thing. HD Tune shows all drives running in UDMA5 while in IDE mode
and says the drives are rated for UDMA6. In AHCI mode, HD Tune says
they're running at UDMA7 even though Windows 7 device manager says
multi-word DMA 2.

At any rate, I did some benchmarks with both in HD Tune and the difference
was negligible. IDE mode actually gave a slightly higher read avg. but it
was so little difference it could easily change from one test to the next.
If the drives were really running in Multi-word DMA2 under AHCI, I would
have noticed a big difference.