Hi, I have the exact same pc configuration as you, and I run the game on ultra settings (no ubersampling) with 40-50 fps in most situations.
bye and good luck with your new pc

Difference between a 6870 and a 6950 is currently about $50. I would go for the 6950, which can be flashed to a 6970. But the 6870 is still more than adequate.

I would go with more than 4GB RAM. On a 64-bit host, the game will use 4GB just for itself, forcing Windows to compete with it. RAM is cheap at current prices.

For a Phenom II x4 and 6870 (or 6950/6970), get a substantial power supply too. At least 500W from a good maker. And get a case with good airflow (I like the Coolermaster HAF series for cheap cases).

I am thinking of getting a corsair 650 watt powersupply and this case:

http://www.amazon.com/gp/product/B000GQMHBI/ref=ox_sc_act_title_1?ie=UTF8&m=ATVPDKIKX0DER

If I wanted to get a 6950 would 650 watts be enough?

Probably ...

You'll have to look up the wattage on the particular card and its cooler.
In addition, what else you're going to have in the computer will make a difference.

For instance, I'm running 5 hard drives and they all need power.

Yeah, that's a nice case and a good deal on it. 650 watts, especially a Corsair TX650, is fine. I wouldn't go for anything less with a high-power graphics card and multiple drives.

I actually only have a 5870 with the same cpu and all options turned up except ubersampling and cinematic depth of field, so you'll have no problems at all. I would say it is fine with one Graphics card also. If you are yet to buy the 6950 maybe shop around as different manufacturers (ie sapphire etc) power needs can be signifigantly lower than others.

sorry, but i don't understand how 8GB RAM would improve the game's performance...

I agree that more than 4GB of RAM is a good idea (RAM is ludicrously cheap right now), but it will have zero impact on Witcher 2 performance. The Witcher 2 is a 32-bit process, and unless you are running four virtual machines and an Oracle database in the background, 4GB will give The Witcher as much RAM as it can possibly use.

I am running a 6950 with a 530W power supply. You don't need a 650W. Heck, here is a system that uses TWO GeForce 560 Tis (each of which use slightly more power than a 6950) and that system only has a 650W.

Personally I would get Intel 2500K and either nVidia GTX560Ti or ATi 6950 (both are good), but it would be a bit more expensive maybe.

I missed this. You can save yourself a chunk of money by getting different RAM. Nowadays, there is absolutely no benefit to having RAM clocked higher than 1333mhz (or even 1000mhz really). This stuff is really good in terms of reliability and it's just as fast: http://www.newegg.com/Product/Product.aspx?Item=N82E16820139046&Tpk=Kingston%20KVR1333D3N9%2f4G.

The reason for more than 4GB RAM is the behavior of "large address aware" (LAA) programs on 64-bit Windows.

A 32-bit LAA program (TW2 is one) can use up to 3GB on 32-bit Windows but up to 4GB on 64-bit. That's good, means you can keep more of the game in the working set.

The problem is, TW2 is not the only thing demanding memory. Everything else in userland, including parts of Windows itself, is going to compete for memory. This will result in TW2 and other userland programs stealing memory back and forth, and TW2 will have to reload memory that it steals back. Now you get "hard" page faults, the disk gets involved, and the disk is the slowest component in your system, even if you have an SSD.

There's also the 4GB limit to think about. That limit is only the memory that can be in the working set. You can actually use more than that, but you have to do it by stealing pages from yourself. This is not as bad as it sounds: if you have a resource on a page, but you have to page it out to make room under the 4GB cap, it doesn't actually go away. It becomes available for page thieves, but if no page thief needs it, it doesn't get cleared. When TW2 wants that resource back, Windows is smart enough to know it's already loaded, and it comes back in via a cheap "soft" page fault.

Thus the general rule for configuring memory for a real-time system: you should have enough that you don't have to use the disk while your important program is running. On a Windows host that runs 4GB LAA programs, that size is greater than 4GB, preferably a good deal greater.

Since the pricing on 2x4GB kits of RAM is very favorable nowadays, there is little reason to go with less.

Thanks for the help guys. I think I am going to go with more ram just to be more future proof.
For TW2, would the 6950 be able to max everything except ubersampling?

I am also wondering about Intel vs. Amd CPU's. Is it really worth the extra money to go with an Intel Chip?

I think the 2500K is a better CPU, but it shouldn't make a difference for the Witcher because it is GPU bound.

You'll be able to run everything maxed, but you won't get 60fps. Figure 45 average with a low of 30 (assuming 1920 resolution). That's what I run and I've been happy with the experience. It's not a shooter.

I'd say an AMD build with socket AM3+ is worth considering. There's a limited selection of AM3+ motherboards now, and the new generation ("Zambezi") CPUs are due in the third quarter (maybe July). These will obsolete the Phenom II x4's and x6's, which will be end-of-life by the end of 2011.

So consider an AMD Socket AM3+ build with an inexpensive Phenom II x4 or x6 now, with the intent to update to a "Zambezi" CPU when they become available. An AMD build without Socket AM3+ support would be buying into planned obsolescence.

But if you want best performance right now, go with Intel. The Sandy Bridge Core i5's (2400, 2500, 2500K) and Core i7's chew up and spit out the AMD offerings. Even the lowly Core i3's (2100, 2120) are price-performance competitive with Phenom II's.