Pre-Installed MacOS: X 10.4.9 (8P4037) Maximum MacOS: X 10.7.5*
This machine usually requires the fan syncing software found on the original system installation disk after an overhaul. The hacked Mavericks may be some of the problem.
First get that installation disk.
Next, I disconnect the hard drive and see if it will boot from the DVD.
Address the problems one at at time. Run the AHT from the installation disk without the hard drive(s) connected. Use an old Serial ATA (3 Gb/s) hard drive and see if you can install a system. After you have a clean running machine you can look at putting the hacked drive back in.
I also take it back to the original RAM configuration using matching sticks if that has been altered.
This machine last sold on eBay for $300, so try not to spend two days working on it.