Please take a look in the Asus forums if you feel like, there are several post regarding the issue with 2gb of rams built up by 4x512mb DDR. And also the solution to the problem -> Use 2x1gb DDR.
Want to know something? The only difference between the nForce 4 SLI and the nForce 4 Ultra is the fact that the SLI version has SLI unlocked and comes with SLI support directly. There are ways of unlocking some nForce 4 Ultra so that they support SLI.
Most Intel motherboards will not slow down the memory when getting over 1gb RAM. Had a intel rig which could handle 1.5gb ram without slowing it down. The only reason that it would slow it down would be because one of the modules is either defective or rated as 333MHz.
Please trust me on this, most, if not ALL, nForce 4 based motherboards will handle 2x1gb modules in 200MHz.
And what do you mean with "Ahhh you think its running at 200, but It isnt..". I can tell you that I know for fact that it runs at 200MHz. POST shows it does, any windows overclocking utility shows it does. I have enough experience with computers to know when something runs at the speed it should and when it does not. So please, accept the fact that nForce 4 and the A64 memory controller (it is still much much more depending on the CPU than the chipset when talking about the A64) can handle 2x1gb modules at 200MHz.
To go further and avoid more posts please consider this;
the memory controller is built into the CPU (as stated already), it has nothing to do with chipset limitations (chipset on the motherboard). Therefore it won't be any difference between different motherboards. Guess why no nForce 4 based system can handle 4x512mb modules running at 200MHz. Got a good guess? Well because it is the memory controller in the CPU that is the limiting factor. Therefore it won't matter if you buy Abit, Asus, DFI, Gigabyte or whatever the CPU is still the factor (the memory controller in it).
Now maybe something like "newer A64 CPU's has an upgraded and better memory controller and can therefore run 2x1gb modules at 200MHz" will come?
Truth is, there is a new memory controller. It is upgraded and it is better. But it has not changed when it comes to the memory setup in terms of number of modules. It has changed on how picky it is about ram. The new ones will accept cheaper brands of ram and run them better.
No offense is intended with this post, nor am I trying to make you look like a fool or anything similar. I am only telling you how it really is. If you feel offended report me or whatever... Still friends?
Edit: crap that was a long post