HDAMA Onboard SATA issues with installed RAM > 4GB

[Eric Wort]

First off, I have never been able to get this machine to boot any 
release of Fedora Core with more than 4GB of RAM installed, as it starts 
having SATA seek errors.

Configuration is as follows:
Dual Opteron 248's in a RioWorks HDAMA board
4 or 8 GB worth of 1GB Corsair registered DDR400 sticks
2 SATA 74gig Raptors (for the OS)
2 SATA 200gig Seagates
3 PATA 200gig Seagates
SATA drives are hooked to the Promise PDC20319 onboard controller

Upon trying to upgrade to FC4 from FC2 with 4GB of RAM in the box, the 
machine would crash just after detecting the videocard in anaconda.  For 
some reason I decided to randomly toss in the other 4 sticks(bringing 
the total to 8GB) and try the install again, which worked perfectly 
during the entire install.  Upon rebooting the fresh FC4 install, it had 
the same SATA seek errors as normal.  Taking the box back down to 4GB 
allowed it to boot right up.  Does anyone know why the install kernel 
would have zero problems with an hour long install, while the stock 
FC4smp kernel can't even boot without seek errors?  I imagine it may be 
due to the install kernel being single processor, but I am not sure.

Thanks,
Eric Wort