I have used various white thermal compounds and gotten good results, however arctic silver is better. On a PIII it might be only 2-3 degreesC better but I have an amdk6-2 500 running at 86F during UT (on same machine I let a cable stop the fan on the golden orb and the alarm went off at 140F but didn't crash)for hours on end. I have seen temps rise to over 120F with Good Globalwins and to 113F with golden orbs. Thats way more than 2-3 C. Seems it might be like the articooler If you ever find one. The hotter it gets the better it works. And I have done my own tests and it is worth it to ME. Just about anything will work on pIIIs I have even seen them run without thermal compound at all. Get hotter chips and they may need it. HTH