Hello, I'd try this....
Clone 10.4 to the 10.5 partition, then install 10.5 on the cloned partition... thinking there was some "enabler" software on the 10.4 partition.
Also, when booted from 10.4, take a look at the system.log on the 10.5 partition.
Open console in Applications>Utilities, check the system log for the date/time of the last 10.5 startup.
Klaus; thank you for your response and the links. pulled out video card and put the original card back in, pulled out an ide card that added extra firewire and usb ports, and there was no improvement. starts, chimes, grey screen, apple logo, shut down - total time elapse 35 seconds. as i mentioned did the first install on a hdd that was successfully running 10.4, over wrote it with the 10.5; I then put a virgin hdd, formatted it and did a clean install with the 10.5 OS with the 35 second start to shut down cycle as a result. now can't get the machine to boot from any CD or DVD, tried 10.4 and even drug out an old OS 9, held down the "c" key during startup, still shut down after 35 seconds. ugh!!!
PS; all jumpers are properly set.
BDAqua: thanks for the reply, but don't think I can do what you recommend; i can't get the system to run for longer than 35 seconds. and to repeat, after the 10.5 over write of the 10.4 OS failed i did a clean install of the 10.5 OS on a virgin hdd, that i partioned using the 10.4 install #1 cd. i can't get the system to run for longer than 35 seconds !, i have tried to boot up from the 10.4 cd, no luck, even tried an old OS 9 cd still no luck (holding down the "c" key during startup. pulled out the 32mb vid card and put the original vid card back in, still no luck. about ready to take a powerful ceramic magnet to the new hdd that has the clean OS 10.5 install that isn't working to scramble it so I can try all over again. could the 10.5 DVD be defective, or counterfeit, it came in an official looking package/box with what looks like an offical Apple instruction pamphlet. got it on Ebay from a reputable seller. during the install it said and did all of the "right" things.
i did a clean install of the 10.5 OS on a virgin hdd, that i partioned using the 10.4 install #1 cd.
Try it with the 10.5 Install Disc... what is the 2z691-****-A number on the 10.5 Disc?
1. Insert the Mac OS X 10.5 Install disc, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu at the top of the screen. (In Mac OS X 10.4 or later, you must select your language first.)
*Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.*
3. Click the Erase tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Highlight the drive, select Partition Tab, then Format type... MacOS Extended Journalled, select the Security Options button, choose Zero Out Data, Erase, one pass... after completion hopefully you'll be able to get a good install.
Oh, does it run forever whilst booted from the Install Disc?