Lines up with what I've read about this board, 1600MHz FSB is a no-go, thanks for proving it for certain.
Bummer the X38/X48 don't support the LGA771 mod. And I doubt there is any LGA771 motherboards that can overclock other then the dual socket Intel Skulltrail board - and good luck with that $$$$$!
One of the other favorites that I have done in the past on good boards such as the Gigabyte EP45-DS3L is take a low powered Xeon L5430 (Harpertown 50W TDP) and set BIOS to run at 1600MHz FSB taking frequency from stock 2.67GHz to 3.2GHz. Not a crazy overclock but the FSB boost does help and the L5430 runs nice and cool at that overclocked frequency. I ran that combo for a years long ago, and should have never parted with it. But I'm happy with my current system considering how little money I have in it! It's running both Metro Exodus Sams Story and Dishonored 2 quite nicely as I play through them currently.