Not having it in AHCI mode will definitely degrade your performance. The good news is that there is a registry tweak floating around in these forums: perform the tweak, shut down, switch to AHCI mode, and reboot.
Two issue with this. First, back up your drive before trying it in case you brick your system. Second, some of us will agree and some vehemently disagree that by running your system in IDE mode for a while you did not benefit from the TRIM command and so you have space on the drive that the drive does not know is free.
I personally do a secure erase and reinstall at the drop of a hat, so I am prejudiced.
Here is what I would do.
(1) download as ssd, install and run (Do NOT need to preform the Benchmark.
In the upper left it will show what driver is being used, (ie pcide - BAD vs what it should be msahci, or for Intel system iaSTor). It will also show "good" for Partition Alignment. If partition alignment shows Bad then you need to do as WyomingKnott indicated - Secure erease followed by a re-install of windows - After Changin Bios to AHCI.
If Alignment is Good and driver is pcide then:
.. (A) perform the convert to ahci
Complements of Sminlel
) Run the Registry Editor (regedit.exe)
2) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
3) Set the "Start" value to 0 (zero)
4) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Pciide
5) Set the "Start" value to 0 (zero)
6) Shut down
7) Start up again, but before Windows boots go into the BIOS configuration screens and change the disk mode to "AHCI". Save the new BIOS configuration and restart so that Windows boots.
END Extract fom Sminlel's post
If this works and As SSD now shows good (msahci for driver). then if Intel go to Intels web site and download latest RST driver and install. AS SSD should now indicate iaSTor for driver.
Next use the system for several days this should allow trim time to return SSD to factory spec., Then run the AS SSD benchmark. If you do not get close to factory spects then:
(A) Do a windows backup of System (C Drive) this will create a system image (will not have to do a reinstall and reinstall all programs)
(B) As WyomingKnott indicated, do a secure erease (While you are at this point verify SSD has latest firmware (Also indicated in AS SSD), if not update SSD firmware.
(C) when done, pop in win 7 installation disk, select repair, repare from image. This will put win 7 and ALL Programs, favorites, emails back onto system. Fifteen minutes later you are up and runing with a factory fress SSD.
If SSD is a OCZ Sata 3 then (A) latest Firmware is 2.13 or 2.15. (B) when using AS SSD you will not get manuf rated speeds as they are for data that is readly compressable (NOT real life) vs AS SSD using data that is compressed for their tests. To compare look up a review (google) and look at what review reports for AS SSD.
If You did homework and bought a Curical M4, latest firmware is 0009 (This boosted performance over previous firmware).