Okay, this is just for Gek025 to explain some things so he can understand completely.
Alright, it works like this, the 1.0-1.5 Xboxes used pin 6 from the LPC bus to get 5v power to the X3 chip. As of version 1.6 Xboxes, Microsoft has redesigned the LPC bus so that pin 6 can NEVER be turned off. This means that if you had a mod chip that was getting 5v power from pin 6 on LPC, then you would never be able to disable the chip.
So, shortly after the problem was realized, all the modchip manufacturers went to an alt 5v point. To use this alternate point, you first had to take pin 6 out (so you don't have two connections to 5v, thus overloading the chip and short circuiting the trace, a common problem that noobs do when they don't read), and then you had to solder a wire from an different place on the motherboard that had 5v power. This way you could again, turn on and off the 5v power, enabling or disabling the chip.
Now, back to his problem. His FRIEND installed the chip, apprently thinking he had done enough Xboxes to not do research properly, he did the same old install that he had done forever, installing without removing pin 6, and without installing an alt 5v cable. This means that he was getting his 5v power from the lpc which couldn't be turned off. No harm done since he is still getting the 5v power, he just can't turn off the box now. He SHOULD be able to just remove pin 6, and then solder the alt 5v wire and hook it to the x3 and have absolutely no problem at all. There is no difference in the two sources of 5v power (pin 6 vs alt 5v on the mobo) other than you can't turn it off, so it would cause no damage to the board.
I hope I helped you out so that you understand the issue now. I don't know if you knew exactly what alt 5v was for, and why the 1.6 xbox was different from the previous xboxes, but hopefully now you do
Oh, and besides, without the 5v, you won't fry anything like you suggest. It works like this...
No 5v power at all (Pin 6 taken out, alt 5v wire not installed) = Chip just plain wont turn on, no damage done, the chip just isn't getting power, so it wont turn on.
Getting 5v from either pin 6 or alt 5v = chip gets power, however if you are getting 5v from pin 6 and have a 1.6, the chip will ALWAYS be on when the box is on
Getting 5v from BOTH pin 6 AND alt 5v = Fried trace on the X3, look in these forums for a tutorial on how to repair the trace, otherwise buy a new X3.