I have a Dual Opteron system I want to upgrade.
It's based on a Tyan Thunder K8W board currently with 2 x opteron 248 cpu's and 4x 1GB dual rank PC3200 DDR ECC ram.

I want to add at least an extra 8GB of ram via 4x2GB sticks,
but I read the K8W will only support 6 ranks of PC3200 ram total per bank of DIMMS. (already got 4 per bank)
So as I understand I would need single rank RAM to utilise all 4 remaining slots at PC3200. Not too easy to find I think.
So can I mix dual rank PC2700 ram with the PC3200 and have it all recocognised (as PC2700 which doesn't have the 6 rank restriction)
or do I need to ditch the PC3200?
Also any idea what the max amount of ram this board will actually take? Tyan website says 16GB @PC2700 but kingston website suggests up to 32GB. Anybody tried more than 16GB?

I want to go to 2 x dual core CPU's. Will the Opteron 800 series work in this mobo, i.e. 880 or 885.
tyan website doesn't say so but I've heard some say it does. I thought is should work fine, but don't want to spend the money and get burned.
I only ask because I might be able to get a couple of these more easily/cheaply than the 285's.
Note: I have checked the mobo revision is correct for dual core / E stepping.

As an iside I would love to know what the difference is between an OSA885 (for example) and an OST885 opterons,
both have same specs but the OST seems to be much more expensive (when searching ebay).

tyan says it supports 265*, 270*, 275*, 280*, 285* (1.8 - 2.6 GHz) if the board's revision number says 04MOAb.

You dont need the 800 series opteron unless you plan on using more than 2 processors on a board. that should save you some dough.

http://www.tyan.com/archive/suppor [...] _revID.jpg

Tyan says max is 16 Gb, i would stand by that. What are you doing to want that much memory? with the new dual cores you would be limiting yourself to go with anything but PC3200 memory, i would not mismatch them, buy more of what you have. Registered pc3200.

Thanks rockbyter, but I think you missed the point of my questions a little.

I can stack an extra 4x2GB PC3200 sticks of ram in it, but I fear it will not recognise it as it's supposed to only accepts 6 ranks per DIMM bank when using PC3200. The question is can I do this but make it see it as PC2700 and and therefore use it all.

Also re CPU's, I can get hold of some 885's easily. So if they would work that would potentially be cheaper for me than getting the 285's.