It's not that you HAVE to use DDR 333 RAM, it's that when you run in a four stick or 2GB configuration, you won't be able to boot without underclocking your RAM to DDR 333. Using DDR 400 RAM is fine, you'd just have to underclock.

However...

The new DFI ATI CrossFire board reportedly (According to AnandTech anyway) for the first time allows in an AMD board the ability to run four sticks or 2GB at DDR400 AND at 1T.

Rather than get DDR333, makes more sense to stick with your DDR400 and get the new board.

Don't think it's your RAM, I think it's your GPU.

Fear runs extremely smooth on my AMD64 3000/6800 Ultra rig @ 1280x960x32 with all the performance settings set at medium. And I've got "only" 1GB 3200 RAM too.

On reexamination of your specs, by golly, you're right....

XP optimization perhaps? Running processes in the background eg. Konfabulator? Defrag your HD?

Cos the 6800Ultra handles FEAR for me quite well. Except for once when after about 2hrs with the aircond off I got a severe case of artifacting: even after rebooting. Solve by taking the sidepanel off the HomeRig. I suspect that heatgenerator of a Antec 550W PSU. A pile of junk actually. Should replace it with an Enermax...

Ahhh. On the HomeRig, I disable AA/AF.

But on the WorkRig, I've been running at 4xAA/16xAF and I get what you mean. AA/AF is a memory hog. I've got a pair of Corsair 3200Pro sticks in a drawer. Will slot it in to bring the WorkRig up to 2 gigs. Will have to run at 2T though. What sort of FSB clocks are your running at with four sticks?

Can't get the WorkRig to see all four sticks. Even running at stock 200FSB (2.4Ghz); 2T.

The rig boots, All four sticks appear in CPUZ but maddeningly, the XP Hardware Manager only reports 1MB RAM. Tried switching banks, no go.

Perhaps the DFI board does not like that while these are matched pairs, they are not four identical sticks... One pair are OCZ 3700EB sticks and the other are CorsairPro 3200 sticks...

Well, back to 1GB for now...

Wanna trade with me then? 2 gigs sounds pretty sweet to me....

On the S939 boards that I've owned: Asus, Abit, Gigabyte and DFI; I've had generally poor sucess in populating all four memory slots. ALL of them (with the exception of the DFI Expert) will not boot with all four slots filled. The DFI Expert would boot but presumably because they were not IDENTICAL chips, would only recognize two of the four.

My solution was to go with a new pair of OCZ 1 gig chips paired to a total of 2 gigs. The final bottleneck in the system has therefore been removed. Widescreen gaming with full eye candy and no stuttering. I'm rediscovering FEAR at the moment. Am also trying out Quake4....

I'm using a pair of these and they work very well at 1T. FEAR now does not lag even during the crowded fire fights. Am replaying the game as a result of this upgrade!