Are my caviar blacks failing?

Hello! Sorry if I make any mistake in my writing, I am southamerican and I´m not completely bilingual.

A while ago I have a RAID between two 750 GB caviar black and their performance appears to be inadequate. I don´t know why. Here it is a benchmark result in which you can see the low performance:

In another forum they recommended me that I had to make some slices and that my performance would improve, so I did it:

Here you can see that there was not improvement in the performance and I started to ask my self if there was something wrong. When I undid the RAID arrangement  I took the opportunity and made some test individually, these were the results:

You can see that these results are very bad, the speed and the access time. Compared to other hard drives, for example to a Samsung F3, and even a caviar blue (here, in my forum:

I don’t what is wrong with my discs or my configuration. Could you please help me?

Specs of my rig: 

core i5 750

evga p55 le

sapphire hd 5850

audigy le sound card

corsair TX 750

thank you all!

uuuupp! please help me!

!!!please help!!!

my sata 2 caviar black has almost similar result. i will upload the screenshot later. i’m not so sure if i have normal speed of legendary caviar black or not, but seems like barracuda 7200.12 has greater run, better benchmark result and more constantly transfer rate.

i have only single black by the way, and raid 0 blue.