Overclocking
Seeing as the X600 is a reference card, not all of the memory modules have a method of heat dissipation other than dumping heat into surrounding air. In addition to that, the stock ATI cooler for the GPU is used, and in some places it was visually verifiable that the cooler was not making contact with the ram, so we didn't have the highest hopes for overclocking this X600.

Rage3D's ATI Tweak was used to overclock the card from the default 500/365 core/memory. In our tests, the limiting factor seemed to be the memory more than anything - keeping the memory at stock speeds, the GPU was able to run stable at 560 Mhz. The limit for the memory was 415 Mhz, where anything greater would result in instability. Combined, the maximum overclocked achieved was 535 Mhz core, 407 Mhz memory. This overclock was torture tested for at least 3 hours of 6 times Anti Aliasing and 16 times Anisotropic Filtering, and then was used for 2D and 3D interaction for at least another 3 hours.

Here is how the overclocked X600XT performed against itself at stock speeds:

Doom 3: Overclocking

Call of Duty: Overclocking

Moderate gains were achieved with overclocking, the most noticeable being Doom 3 at "High" quality without Anti Aliasing or Anisotropic Filtering. Call of Duty also saw a large increase in speed at 1280x1024 with 4 times Anti Aliasing and 8 times Anisotropic Filtering.

3D Image Quality
ATI has consistently had good image quality, and the Geforce FX series has shown it can match ATI's quality. The two compared images were taken at 1600x1200 with 4xAA and 8xAF

X600XT: 4xAA 8xAF (90kb)
PCX5750: 4xAA 8xAF (90kb)

I was surprised to see a very small difference between the two images. I found that the x600's edges seemed to be a bit less jagged (which is accounted for by differences between nVidia's and ATI's Anti Aliasing implementations.) However, other than that small discrepancy, the image quality for both cards seem to be on par. If forced to choose between the two, the x600 barely beats out the 5750.

2D Image Quality

We loaded up a 1600x1200 image normally used in our video card reviews. I also pulled up an HTML document with various sized fonts to judge the text rendering. The document used white text on a black background, and vice versa. The screen resolution for all tests was 1600x1200 @ 85Hz on a 19" Dell P991 Trinitron.
Scores are subjective, but having worked with many video cards the last few years, I got a pretty firm grasp on what card renders 2D better than the others. The scores will be out of 10, with 10 being excellent.

	PCX5750	X600XT
Black Text (12 Pt)	9	9
Black Text (6 Pt)	7	6
White Text (12 Pt)	8	8
White Text (6 Pt)	6	5
Bitmap Quality	7	8

Overall, smaller text, especially the 6 pt white text seemed to be blurry on the X600XT.

Final Words

When reviewing a product like the X600XT, it's important to keep in mind what the product's purpose is - in the case of the X600XT, it is to provide a budget/mid-range PCI-Express solution. In this respect, ATI has definitely succeeded - the X600XT is within the boundaries of mid-range cards, and performs well. The PCI-Express implementation has proven to be flawless (at the time of writing,) absolutely no errors were caused or detected during the benchmarking process.

The X600XT performed well at 1024x768, its performance declining as the resolution increased, or as Anti Aliasing or Anisotropic Filtering was turned up, however most gamers can deal with 1024x768 on a budget card.

On the flip side, the PCX5750 costs $140 USD, and performed somewhat closely with the X600XT. Due to how low the benchmark scores were on the PCX5750, I would put the X600XT in a class above it, as the X600XT is in a different price range, and is justifiably more expensive, as has been seen in the benchmarks.

The X600XT is one of the better mid-range solutions that is available for PCI-Express, though in some cases, it has been outclassed by nVidia's 6600 GT. We'll be sure to compare apples to apples - the X600XT against the 6600 GT when we can, but compared to nVidia's other mid-ranged solution the X600XT seems to be the better choice for the PCI-Express mid-range video card dilemma.

Pros: 1024x768 gameplay is suitable for most games, when bundled, the X600XT will have a great bang-for-buck ratio.

Cons: Gameplay above 1024x768 is limited, AA/AF seriously decreases performance.

Bottom Line: If you need a PCI-Express card right now in the $175 USD range, the X600XT is a good choice. Bundles and VIVO will add to the value of the card. For a gamer who doesn't need to have an incredible resolution, or simply doesn't have a wad of cash to throw down on a video card, the X600XT is a great choice. However, if 1024x768 isn't your bag, or you absolutely need Anti Aliasing and Anisotropic Filtering running in every game, the X600XT is not for you.