Hello,

I have found this mailing list entry with the same problem I currently have:
http://www.mail-archive.com/linux-raid@vger.kernel.org/msg05835.html

I have made some tests on 4 different mainboards and 2 different SIL 
3512 cards:

3 mainboards have the VIA KT133 chipset. On each of these mainboards I get the
checksum problem with both cards if I want to use a softraid.

1 mainboard with a SIS chipset works fine with both cards.

It seems that the combination VIA mainboard chipset (KT 133) + SIL 3512 
+ Linux
softraid does not work.

Regards
Oliver Paulus