Hello,
Recently i have bought two 160 GB 7200.10(ST3160215AS) seagate hard drives and put them in RAID 0. I have a quite old motherboard (ASUS P4V8x-x) which has integrated VIA RAID controller.
The average sequential read performance is ~50-70 Mb/s , and write performance - ~40 - 50 mb/s.Random write and read performance is significantly worse.
I expected these drives to perform better. What can the problem be ?

Regards,
Lukas.

That is approximately the perfomance of a stand alone drive, so you're right, the performance is low.

I'm not even going to pretend I know anything about your chipset or RAID controller, but perhaps there is a RAID utility available from Asus that can change a setting about this, perhaps related to caching.

My new RAID5 build on a ICH8R had writes of about 6-8MB/s. After enabling caching, it went up to 50-60MB/sec, depending on where the data came from (one HD would only let it go to 35MB/s, but it also copied at 35MB/s to my RAID10 array, so I don't think it was the ICH8R's fault).

If your motherboard supports SATA 3Gb/s, did you remove the jumper on the HD to enable that mode?

depends where you get your performance from, theyre sata 2 drives and i dont know if your mobo supports that, i so did you remove the jumper on each HD?