P4B533: FSB>173 = problems!

I have a P4 SL6RZ Costa Rica which runs smoothly@3112 (173 FSB) with default vcore under [email protected] volts. But even if I up the vcore to 1.6 or even 1.65 it wont give me as much as 1 MHz more! I find that very, very odd. I know at some point, upping the voltage wont help anymore, but from undervolting to 1.65 not one single MHz extra? That smells like motherboard limitations to me and not a CPU maxed out. Or what do you guys think?

Btw, there´s not a chance it´s my ram thats holding me back, cause it´s PC3000 and I´m running at 4:3 CPU/MEM-ratio when testing CPU speed to ensure one problem at a time. Bios is 1014 (have also tried a tons of other BIOS versions)

And one thing more: The Q-fan just DOES NOT WORK and it´s really bothering me. Anyone knows of faulty Q-fans?

Please help, I´m starting to hate my board!

blah

i ran the 2.2 p4 in that board @ 2771 with koolance water case. w/ 2100 ram. it also wouldn't go any higher than 173bus. i think you are right. it's the board?