GA-MA770-UD3 rev. 2.0 - HDD peformance fluctuations

[Decebal]

Hello,
My  computer(new) runs very slowly and I initially  to suspected  my hard disk for this annoying situation. I used HDTune 2.55 for repeatedly testing/checking the drive. I also attached a graph where you can see what I mean.
Later I discovered that the hdd  it is not at the base of the problem, because  I inserted the drive in another computer and the drive performed properly. So, I think that  the hdd fluctuations are just a consequence for something else not working properly.
I also checked the cables/conectors that connect to that drive and  I changed the sata cable and the power supply just to be sure.
My configuration: GA-MA770-UD3 (rev. 2.0), AMD Athlon X3 at 2.7 GHz, 2GB DDR2, AMD Radeon 5750 1GB, PSU Chieftec GPS-550.
Are there any mandatory bios related sata settings for the GA-MA770-UD3 (rev. 2.0 ) I shoul have in mind when installing this drive?
What software should I use to check if the sata controller is faulty? What else should I check?
Any other suggestions are welcome. 
Thanks in advance.

[absic]

Hi there,

the first thing I would do, is check which BIOS version you are running and if it is not the FKD (download from here: http://www.gigabyte.com/products/product-page.aspx?pid=3097&dl=1#bios  )then I would update to that to see if that improves things.

If you do need to update the BIOS use QFlash and not the @BIOS utility and remember to disable the "Keep DMI Data" Option on the Qflash Homescreen before actually running the update.

[Decebal]

I already updated the bios to the latest, but i didn't use qflash. I used the software that came with the firmware update. But still no improvment even with the updated bios.

[Dark Mantis]

It is possible that something went wrong then and if you used @BIOS this is quite a possibility. Reflash the BIOS using QFlash and see if that helps. Also make sure that you are using the first port SATA2_0 and setting the port to AHCI mode.

[Decebal]

Reflashing with Qflash and setting the drive to AHCI and port sata2_0 doesn' t help either.
The thing is, that this slowness occured before I flashed the bios, it  was from the beginning kind of slow and I didn't know why.
Now I got some time to research and test a bit further before I send it back for guarantee.