Cannot get past Apple logo for a fresh install Leopard

Hi all,

After turning the storage room upside down I found an old G5 Quad late 2005 lying free, decided to make a fresh install and assign it to the interns. There were no disks and ram on the motherboard so I got appropriate ram and a HDD. I have an installation disk which I am pretty sure that works as I have used this disk a couple of months ago.

When I start the computer with "c" key pressed, installation disk starts to work however after some 2 or 3 minutes the spinning circle under the apple logo gets frozen and the fans start to blow loudly. I have also tried the option key "alt" and selected the installation disk which appeared on the screen, same thing happens.

I have tried

*putting in different RAM modules

*using different HDD(all checked S.M.A.R.T. status shows OK)

*using different DVDROM drives(including superdrive, HP DVDROM, LG DVDROM)

*resetting NVRAM( pushing the power button and not letting it go until Open Firmware console comes, reset-nvram , reset-all commands run)

*taking out the BIOS battery and unplugging the power chord, waiting for 10 mins

*formatting the HDD on another mac, selecting the partition as Apple something something instead of GUID

I am out of ideas, I can even try voodoo if it would help. Anybody have any idea? please don't tell me that the motherboard needs to be changed.