Kernel Panic at Start up. Nothing i've tried works.

Hello all
Sorry if this issue has already been discussed, but i searched the forum
and couldn't find a solution. I've been getting a Kernel Panic crash at start up
and cant get work on my mac. i've had this mac since the summer of 2008.
All i've added was 10 gigs of ram ( all ram is identical ). I tried switching out the ram to different slots, and also tried starting it with just 2 gigs using different sticks. The hardware test finds no errors. I can't boot up from the install disc. My optical drive is working because it i can boot up from the hardware test from the install disc. I've tried all the keyboard start up options and get the same result ( Kernel Panic Crash ). Windows runs fine through boot camp and all apps work fine. I did a fsck but it seems my drive is fine.
Does anyone have any ideas? Please help .
Thanks

G'day and welcome to the forums.

Well memory is your # 1 suspects at this stage. The majority of KP are put down to dodgy memory.Did you get the modules from a Mac dealer and it does help if you provide details of your computer and operating system.

Earlier model Macs in particular are extremely sensitive to memory specifications, and these must be low density. Most PC memory is cheaper high density which may well cause KP attacks. And how can Windows run fine if you are getting the KP at boot? You pulling our legs?

I'm getting a kernel panic when i try to boot up leopard. When i boot up windows via bootcamp the machine runs fine. All memory sticks are identical (OWC) from mac mall. All memory sticks seem to work fine because in windows its reading 10 GB.
BTW
Mac pro 8-core
2.8 GHz
10 GB

So you've done:

SMC Reset?
PRAM Reset?
Safeboot?
1. If you can get into safeboot
........2. Delete your Caches
Repair Disk when starting up to OS Install DVD?
Repair Disk Permissions when starting up to OS Install DVD?

If you can safeboot - take a look at the log and check if you can tell it's been stopping when trying to load a particular kext. Ex. I've had one that was a kext for one of the Paragon apps that was not compatible with an upgrade. Removed the kext and was back up and running again.

Thanks for the advice.
I've tried SMC Reset, PRAM, NVRAM, to no avail.
Cant boot up on Safe Mode.
I can't find anything on why it won't boot from the install DVD.
I've tried

1 Holding "option" at start up and selecting the DVD
2 "C" at start up
3 "Target Disc" using a Macbook

The Macbook reads the DVD fine.
I've backed up everything but i can't do clean install cuz my mac wont
boot up from the DVD.
Is there a way to force the machine to boot up from the DVD in "single user mode"?