Sorry ive just read ur post properly, i guess thats the problem with posting on the fly, ive now edited my post to 850mhz, hope the guy didn't use it as it was, although i think it would just not work set outside of the available freqs...... confirmed

I've been clocking all the way up to 1.15ghz and its been rock solid, although i never leave it so high for long just to play psx4all, i use ideal settings for browsing and when i need a bit more speed, and underclock 250-500 for idle (still struggling to make 125 stick)
all in all ive had nothing but positive results, with a few tweaks im now getting much improved battery life and have had zero overheating or data curuption, (i think im one of the lucky ones with a super chip)