I had mine at 250/555 for almost a year and only got rid of it for a G4. Not all cards will clock the same, but a safe bet is 240/540, start there. I could get the core to 255, but not very stable once it got warm and the mem won't go much higher than the 555.
Wow that's some great overclocks I found that mine seems stable at 220 mhz core and 475mhz mem,... seemed fine at 230mhz core and 490 mhz mem but after repeated runs on 3dmark 2001se it rebooted once and froze the other time this it after repeated consecutive runs of 3dmark. I probably wouldn't have any problems I wouldn't imagine if stay away from super intensive games at the higher overclock. Again your cards are unmodified stock cards right? Still I don't feel too bad I got an 900 pt increase in 3dmark2001se at the very stable lower setting.
I had a Verto GeForce3 Ti200 and just changed it for a XFX GF4Ti4200. My GF3Ti200 ran stable at 220/500 with a new fan on it, I used a Cooler Master designed for Athlon XP and plugged it to the sysfan on the mobo..., I would´n go any higher than 290/480 without replacing the fan...
I have the Winfast Ti 200 and my card will only run stable at a speed of 195/445. I usually run it at 190/440. How does one replace the fan and heatsink on the card? I don't understand... i have noticed that everyone is able to run their GF3 200 card at at least 220/440 but my Winfast board will not run at those speeds is that manufacturer dependant or is it quality dependant? Also, if i ever upgrade to another board which manufacturer is the best to upgrade to?