game ran fine with evga 570GTX overclocked and also ran fine with my newer evga 970GTX also overclocked PRIOR to that early April patch.
so no have not tried to run a standard clock.
and yes i have tried to turn off FXAA. i've tried everything in Naval Action game at LOW, MEDIUM, HIGH, ULTRA, FXAA ON, OFF, AA OFF, 2x and 4x, and set FPS to 15, 30, and 60 to no avail. for me it all seems related to something from the patch 2 weeks ago. system ran smooth without any glitches prior to that.