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I want to add a new SSD and use it as system drive with Windows 7 x64 installed.
As driver I chose newest Intel Rapid Storage driver (not MSAHCI). I know that I have to use AHCI as BIOS setting for optimal SSD read/write performance. But I'm also using 2 normal hard drives as separate RAID-0

SSD: Windows 7
hard drive: RAID-0
hard drive: RAID-0

If I set my BIOS on my Asus P5W DH Deluxe to AHCI, my RAID-0 cant be recognized
And If I'm using RAID as setting, maybe my SSD has not its top speed. But I'm not sure about that.

In short:
AHCI > no RAID-0
RAID > no optimal SSD performance (?)

Now my question: Can I use RAID as BIOS setting and be sure, that theres no decrease in SSD performance?


Google finds so many articles with similar topics and my head is just exploding. Two examples:
- set AHCI and after installing OS switch to RAID as BIOS setting... what?
- use a diskette and F6 while installing Windows 7... really? O.o I thought those times are gone

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Honestly you won't notice the speed difference between AHCI and RAID, even if you only had the SSD in your machine. –  user3463 Dec 2 '10 at 18:02
    
@nixda - Why the unaccept two years after the fact? o.O –  Shinrai Jan 2 '13 at 16:23
    
@shinrai I recently expanded my system with additional drives and recreated the raid. I did some research and found this link which states "RAID is more advantageous for people compared to AHCI" and I remembered this question. I think there is a difference between them and I should unaccept it so no one get pointed in the wrong direction. Now I have read my question again and I saw I was just asking about speed, not about differences in general. I will accept it again. Nevermind :) –  nixda Jan 2 '13 at 16:36
    
It's worth noting as well - that link is really out of date. AHCI has not been Intel-exclusive for quite some time. (I would say most of what it says is still relatively true, though.) –  Shinrai Jan 2 '13 at 17:01
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2 Answers

up vote 3 down vote accepted

RAID should support everything AHCI does for an SSD that isn't actually in an array; no reason for concern.

(On a tangential note, I've benchmarked better speeds using the msahci driver than the Intel one even on Intel drives. If you're that concerned you might check it out.)

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There is one important thing to be noted here:

As soon as your RAID is built, it is identified by the OS as a single whole and you cannot access its constituents separately. This may be inconvenient. For example, you won't be able to update the firmware or view the S.M.A.R.T. information or perform a Secure Erase for the SSDs in your RAID. But the biggest problem is that the OS won't be able to use the TRIM command which is supposed to protect SSDs from performance degradation.

To sum up, SATA RAID controllers, including those in modern chipsets, do not support the TRIM command. As a result, the array’s writing performance degrades over time whereas single SSDs are less susceptible to this problem.

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Depending on the SSDs, their manufacturer may have software that will let you mess with them individually even through a RAID array (for the purposes of upgrading firmware, etc). I know Intel supports this to an extent. –  Shinrai Aug 20 '12 at 19:04
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