Q: Does ABIT KR7A / KR7A-RAID / KR7A-133 / KR7A-133R / AT7 support ECC memory?
A:

KR7A-R can boot up with ECC memory modules installed, but without ECC function.

It supports up to 3GB of un-buffered memory and 4GB of registered memory. Please  note  that the maximum DDR memory support of KR7A is about 3.5G instead of  4G. This limitation is caused by PC architecture and the missing 0.5G memory address is reserved for PCI I/O space, AGP aperture mapping space and other onboard device I/O space. Thus, although the KT266A datasheet claims the memory support is up to 4GB, the system only uses  about 3.5GB with four 1G DDR sticks installed. In another words, the BIOS and operating system will only report about 3.5GB.    

Please refer the FAQ: http://fae.abit.com.tw/eng/faq/qa/2001/2001121102.htm