John R Pierce wrote:
Nobody answered my original question, can you fill a motherboard with four DDR2 slots up to 8GB at all?
Intel's DP965LT motherboard claims 8GB support with 4 DDR2 dimms. http://developer.intel.com/products/motherboard/DP965LT/index.htm
if you have 4 dimms in this chipset, you're limited to 667Mhz memory bus, with 2 dimms, and the right memory timings, you can get 800Mhz memory timings. All memory used in P965 chipsets must be 1.8V compatible.
I peeked at prices on newegg, 2x2GB dimm kits are $430-$600 each, so 8GB ram will cost between $860-$1200.
I noticed, they do exist!
This whitepaper on 965 chipset memory technologies details the specifics of whats supported and how the memory timings interact. http://download.intel.com/design/chipsets/applnots/31320702.pdf
I see nothing about any degrading above 4GB, except that 2 x 2GB DDR2-800 is supported, while 4 x 2GB runs at DDR2-667 speeds... I wonder if the previously discussed performance degrading on the Asus board was in reference to PAE required to allow 32bit OS's with > ~3GB ram ?
That's what I understood. Not only Linux but also Windows seems to not work properly with large memory configurations. This ASUS board is no longer on my wish list.
In the mean time I contacted Dell. They proposed a Dell Precision with a Xenon 5150 processor. The price is different of course, but the memory is now fully buffered (FBD) and having 8 slots leaves room for upgrade to 32GB :-) Machine can be deliverd with RHEL4, so I trust Centos will not be a problem to install.
Theo