weird raid0 scores on HD TUNE HELP

Hey guys new to the forum, got a few questions for you experts. Ok i have a gigabyte ep45-ds3r board, core duo e8500 , im running raid 0 on it with the intel raid. Ok first i installed 2 160 gb western digital cavs in raid 0 ran Hd Tune the home version and was scoring a 157 average transfer rate with max of 200mb , low end was like 94mb, burst rate like 140. I decided to get more storage space so i bought 2 samsung f spinpoints 320 gb drives heard there really good in the reviews. Im running them in raid0, so i ran the HD TUNE again, my scores have came way down, now my max transfer rate is 150 mb and my average is only 130mb, but my access time came down to 12.7 from 15.7 with the wd hdd. So my question is why the huge drop in performance on hd tune ? i actually thought the performance would go up, the f samsungs beat up on the wd in the test ?? what is going on ? the samsung is rated for 3gb per sec, i have that on my board, its almost like the drives are only running at 1.5 gb per sec, i have heard there is some issues with samsung and certain raid drivers. On samsungs site they say that sometimes there drive may not be compatable with with 3 gb, and will go to 1.5, what is that, i have never had a harddrive that has issues with raid drivers. So any input would be great, im getting ready to return the drives with that much of a performance drop, i know its only synthetic performance but still something aint right with these samsung f drives hellllllllp. Thanks.

mike