I just tried it out under windows and have very good performance as shown below.
However under Linux, it continues to have unbearable write speeds.
The motherboard is an Intel DG965WH and the system is custom built.
The OS is Ubuntu 11.10 which has the 3.2.0 kernel.
I'm going to try flashing an older revision of firmware and see if the issue is resolved.
- Further Info -
Nothing is showing up in dmesg (other than a mount).
This problem is present in both AHCI and Legacy controller modes.
Other hard disks in the system enjoy 80+ MB/s write speeds.