Well, after I got my 3 chips, I was totally torqued at first. They sent me the chips in one of those plastic chip carriers, and they had bounced out and managed to bend a lot of pins on all 3 of them. I called VegaPc about it, and they offered to x-ship me new ones, so I figured I'd try first to straighten them myself. Took an hour to get em all good, but they all work now.
The good news: My P5A from ASUS eats this puppy up at 600Mhz! I set the voltage to 2.1, and the multiplier to 2X, and it runs like a raped ape!!
The bad news: Neither of my SIS boards (M590 and M598) will work w/ em!

The 598 won't even boot, and the 590 won't believe me when I try to set it to any jumper setting, even a conservative one. I'm going to be selling 2 of them to my brother for his systems w/ hard jumpers. Moral of the story; Don't try to use a soft bios to overclock, at least on a SIS board.