you would need the OEM DVD the one that says "Apple Hardware Test"
Otherwise it was only with the original OS install.
For further information and the number of threads and outcomes, 90%? of 2008 owners find that ML is not well suited, numerous problems, and that 10.6.8 works best. You may need to take that into account and setup dual boot environmment. Lion may or may not work.
Shame. 10.8.2 does bring support for more Nvidia GPUs. Otherwise, eh.
So get out your OEM DVD and then hold 'd' - and might even pull all the drives, you don't need those present.
Maybe WHY you want or think you need AHT would be more useful.
Thanks for the ideas. Apparently some additional context may be helpful.
(1) Yesterday, my Mac Pro booted normally, but soon the monitor went blank. I had to hold down the computer's on button to force the computer to turn off.
(2) In a few minutes, I tried restarting. Still the monitor's screen was black. In fact, the monitor remained in standby mode. Further, when I tried my second monitor, it also remained in standby mode.
(3) Today, however, the computer booted and worked fine. Nonetheless, it seemed reasonable to run a test on the hardware.
(4) Every month, I run both Apple Disc Utility and Disc Warrior on all drives. Further both programs say all four internal drives are fine.
(5) No peripherals are connected other than the monitor, keyboard, and mouse.
(6) Neither my original Leopard OS package nor my original Snow Leopard OS package came with a second optical disc. Neither of the original OS discs will run Apple Hardware Test on restart with the "d" key depressed.
(7) I suppose that if I never can get Apple Hardware Test to run, and I have trouble with video again, I'll try booting from Snow Leopard (my previous OS).
I hope the preceding helps. Thanks again.
AHT is worthless with finding a lot of the most common hardware problems. And definitely not video cards which would be t he first thing to suspect and swap out to test.
DW use to be must have and I sure found and recommended it over the years. Now.... clone and such, backups, but safe mode and other things.
OEM DVD though came with it and is only place you find AHT. And you say that doesn't work? contact Apple.