Hi, I'm new to the forum, having tries a few others in the past, but looking through the posts here, it seems like a good place to come to get some help.
I've got a Mac Pro 3.0ghz, early 2008 that has a boot problem.
I've checked all of the ram, no problems showing up there, I've reset the SMC in both ways, I've pulled all of the internal drives, booted off those via USB as well as a couple of others using SL and Lion as well but everything comes up with the same result: it freezes soon after the turning wheel comes up, about 15 secs. The only thing that produces a different result is booting off a SL install DVD... that brings up a kernel panic after a couple of minutes.
I've reset the PRAM as well.
That leaves me, as far as I can work out, three possible issues:
1. Bad ram slot, but the POST check is okay and the LEDs indicate all ram is working.
2. Bad video card - GeForce 8800GT installed.
3. Bad logic board.

The last two are virtually impossible to check without swapping them out and that means potential expense if things have to be sent back, restocked etc, presuming that the supplier will accept them back.

Any suggestions as to other possibilities or other software that can check the hardware would be appreciated.