Caviar Black read speeds under 7mb/s

I bought this drive off new egg about a year and a half ago: http://www.newegg.com/Product/Product.aspx?Item=N82E16822136218  Formatted, it has just under 600GB of free space.

The speed is just terrible lately, and I’ve been running low on disc space, I think I’m down to 10gb free space. By terrible I mean 50mb/s burst speed, and around 6mb/s for files larger than 6gigs. Is low disc space to blame for this horrible performance?

normaly is the drive dying by bad sectors

install hard disk sentinel and see the report

maybe its only needing a defragmentation tool

Update:

So it seems the problem is confined to when I’m either A) writing to a USB device or B) transfering files over my wireless network. I tried copying some files to my newly installed 1TB Caviar Black, and my speed was only being limited to 50MB/s+ by the write speed of the new drive.

So can I assume my problem is unrelated to either hard drive?

maybe if you are transfering files over wireless that maybe be normal

in other ocasions its not