The answer is very simple ... DONT BUY XBIT.
I bought the new xbit v1.5 and after modding several xbox's using previous xbit i was confident in modding, not untill i got this new chip. Everytime i try to install the bios and veriify it using xbit's bios software, it reads as an error ... no matter which slot i use, if its 512, 256 or 1mb.
I tried it all but even so i installed this newer xbit on my xbox that uses the older xbit v1.0 and it didnt want to work. I re-adjusted the new xbit v1.5 many times using the pogopins and still it wont boot to any of the bios i placed on the chip. Simple dont buy it...im dissapointed in xbit, they need to have this issue fixed seeing that im not the only one with this problem.
If its not a manufacturing problem then maybe its tampering by the distributor; when i got the xbit i noticed that the write protection part (the top left portion of the wafer board) was already broken off. I purchased from divineo; i never had this problem in the past but id take caution form buying from them again.