Slow burst rate with new WD5002AALX...70mb/s

Hi all, I decided on the new Caviar black WD5002AALX hard drive. It also has a 32mb cache. I'm getting a poor burst rate with it though...typically around 70MB/s. In comparison to my WD2500JS, its has almost double the transfer speed, but this burst speed has me concerned.

This WD2500JS gets around 130mb/s burst.

I also had a WD5000AAKS with a 16mb cache and it performed better and had a fast (120ish) burst rate.

I only have a SATA II interface so I tried both with the jumped on and off to throttle the SATA interface but it didn't change the burst rate.

CPU seems higher on hte 5002 but that is the OS drive...the 2500JS is just in there to test.

Any ideas? Should this be normal? Is it possible my older MB doesn't like the 32mb cache. I would maybe think its chipset drivers but the WD2500JS seems to be fine in the same computer.

I didn't see any new firmware on the WD site but I'm not sure where to look on there.
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  1. Update: I put the 2500JS in as the boot drive and got similar burst speed results. So maybe this is normal?

    Note the 2500 is 64bit and the 5002 is 32bit. In 64bit the CPu usage reports -1.0%
  2. I know what burst speed is but Im not sure how you are defining it nor how you are measuring it. You moved a jumper but was that on the drive or motherboard?

    You need to be methodical in what you are doing. I see three drives being tested at different times - you need to test EACH one in the same SATA port with the same OS to understand anything. 70Mb/s isnt bad for a hard drive - sustained data xfer. There is a whole bunch of things going on with a new drive in a system. If there is data on it the OS will index it, that could interfere with speed. My point is there are many variables at work...

    Is the BIOS set for AHCI or RAID (the RAID setting doesnt make you use RAID)?
    Was the burst rate on reads or writes?
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