Silicon Image 3512 (Raid 0) suffers the write speed

My config:

Motherboard: Asrock K7NF2-RAID (nforce2 ultra 400)
Processor: AMD Athlon 3000 + (13x166Mhz)
Memory: 1 DDR 2x1GB in dual (@166MHz 2.5/3/3/7)
1 hard disk controller: NVraid SATA I Raid 0 (2 Western Digital WD3200KS (320GB SATA II 16MB))
2 hard disk controller (PCI): Silicon Image 3512 SATA I Raid 0 (2 Western Digital WD3200KS (320GB SATA II 16MB))

Here is my problem, the write speed on the Silicon controller is abnormally low. Yet I have the latest bios (4.3.84) and latest drivers Raid (1.0.60). At the beginning I wondered if it was not a problem of write cache but not in the device manager it is enabled (and you can not disable this). Incidentally or not I usually advanced performance does not change the problem. I check the device utility installed along with the driver. I also installed the Silicon raidtools that allows you to enable/disable write caching. If I disable write caching, its even worse! Someone already had this problem? Has an idea of the problem?

You would not be limited by the speed of your PCI slot? (133 Mb/s theoretical, but if there are other things connected, I assume that the bandwidth is divided by the number of devices connected)

Although even limited by your PCI slot, the flows are very low.

I do not because:

1. why would I be limited in writing and not reading?
2. why my other raid controller is not limited?

Also if I copy a file (4.37 GB):
NvidiaRaid to SiliconRaid: 2min20s = 32MB/s
SiliconRaid to NvidiaRaid: 42s = 106 MB/s

nVidia controller directly into the northbridge
silicon external controller must pass by a bus

but why such a difference between writing and reading?

Well this is an incompatibility between the silicon card (or bios/driver) and my motherboard.

- I removed all other PCI on PC ---> Same result
- I turned off all possible devices in the BIOS of the motherboard (Ethernet/floppy/Sound/IDE/SATA/USB) ---> Same result
- I tried all PCI slots on the motherboard -> Same result
- I have tested in the bios setting "PCI IDE busmaster" to enable & disable ---> Same result
- I tried 2 other hard drives (Maxtor 16MB SATA I DiamondMax10) ---> Same result
- I tried another silicon card ---> Same result

- Then I tested the card on another silicon PC (PIII450 in 1998/2 with Maxtor) -> And everything is normal

I will try the other bios and drivers but I smell the scorched!