sata 6.0 running very slow?

You are getting what you are supposed to be getting.  6Gb/sec refers to the interface speed, not the disk speed.  Equate to a highway.  Speed limit might be 75, but put a bicycle on it, and it isn't magically going to get faster.

The extra speed is a waste of money until you get enough disks to saturate the pipe.  Even with 4 disks, you can't saturate it. To be politically incorrect .. you got taken.

Hi rsoxhater.

There is no such thing as SATA 6.0. The new SATA 3 interface is rated at 6.0 Gb/s, that is it's theoretical maximum which you will never see in real life with a 7200 rpm drive.

The only drives capable of saturating the SATA 3 interface are some of the faster SSDs. If you want to squeeze more perfomance out of your current drive buy 3 more just like it and put them in a RAID 0 (performance) or RAID 1 (performance and disk redindancy at the cost of storage space).

Western Digital are being purposley confusing with their marketing here, they are marketing their drives with the SATA interface speed rather than the SATA Series number.

SATA 1 - 1.5 Gb/s
SATA 2 - 3 Gb/s
SATA 3 - 6Gb/s

Yeah man, sorry...your numbers are fairly normal - but still a little on the slow side.  Traditional sata hdd's weren't close to the bandwidth limit at 3g/s...so you should still expect between a 5.9 and 6.2 for your drive.  You'd need an SSD to go higher.  
When you prepared the installation, did you change serial ata from compatibility mode to ahci?  That's typically the most common issue...if you didn't, check your bios settings and let me know.  You can change after the install but need to make a registry edit.  Also make sure you have the latest AMD® SB850 driver installed.

Edit my post above:

or RAID 1 (performance and disk redindancy at the cost of storage space).

should read:

or RAID 10 (performance and disk redindancy at the cost of storage space).
Big difference between raid 1 and 10.
 

@siht  if you use/differentiate Roman numerals and Aramaic numerals there won't be quite as much confusion written, (but not spoken obviously).  

You can see the SATA naming history here http://en.wikipedia.org/wiki/Serial_ATA 

quoting: "(the term SATA III is being eschewed by the SATA-IO to avoid confusion with SATA II 3.0 Gb/s, which was colloquially referred to as "SATA 3G" [bps] or "SATA 300" [MB/s] since 1.5 Gb/s SATA I and 1.5 Gb/s SATA II were referred to as both "SATA 1.5G" [b/s] or "SATA 150" [MB/s]). "
(remember to differentiate also MB vs Mb, Bytes versus small letter b = bits)

So, there is a small difference, some older early mobos might only support SATA I, or if they support SATA II might still only be 1.5 Gb/s

Notice in the article it asserts most physical hard drives go no faster than the 133MB/s of parallel EIDE ATA133 (as of 2009, as of 2010 a very few are a tad faster than that) whereas SSD are way way faster, about the speed of SATA

Exactly as dlethe wrote, it's the limiting speed of the physical drive itself versus the channel bus maximum.  SSD (solid state drive) can go faster, and most especially we're NOT just talking sustained throughput either, we mean latency, responsiveness, "seek" times, way way faster but not measured in Gb/s.  Yes, the idea of the faster interface is so when you have SEVERAL drives (whether raid or just plain several drives) connected you avoid contention and traffic jams.

qikkel - what registry change?