Well I just upgraded and am now running at 140mhz FSB. Temp on the chipset has only gone up to 58 C max. I guess its fine -- the gforce runs pretty close to that temp too. I would slap a heatsink onto the chipset but the Alpha cooler is now partially obscuring it. 58 seems high to me but if Tyan didn't put a heatsink on it then it must be ok -- in a review of the board, the reviewer mentioned the lack of a heatsink but it seems the chip can stand it.
I'm monitoring my temps with AMK's EC2 -- very cool device, up to 8 probes, nice display, plus 2 40mm intake fans.