I didn't know you were on the 4:5 divider. With that in mind, what voltage do you have set for the nb? This board struggles to run the 4:5 divider. For most people it won't even boot. When successful, it takes a significant amount of voltage on the nb 1.5v+. This board is optimized for 1:1 up to 500FSB with very little tweaking or voltage. I know it's not what you want but try 1:1 same settings. Also I still don't think the gtl needs to be changed @ such a low clock.