In my current search (12/06) to find an X800XT AGP card for my ageing PC, I noticed that quite a few so called X800XTs for sale which were definitely not at the speeds they are supposed to be.
Regardless of who makes the graphics board the Graphics Processing Unit is made by ATI and they are the ones who state the specifications for each model. Here is what you should be looking for on each model:
ATIs Product Name - GPU/RAM Clock Speed (MHz)
Radeon® X800 GT - 475/493 - 8 pixel pipelines
Radeon® X800 - 400/350 - 12 pixel pipelines
Radeon® X800 GTO - 400/490 (256MB) , 400/400 (128MB) - 12 pixel pipelines
Radeon® X800 Pro - 475/450 - 12 pixel pipelines
Radeon® X850 Pro - 500/500 - 12 pixel pipelines
Radeon® X800 XL - 400/490 - 16 pixel pipelines
Radeon® X800 XT - 500/500 - 16 pixel pipelines
Radeon® X850 XT - 520/540 - 16 pixel pipelines
Radeon® X800 XT PE - 520/560 - 16 pixel pipelines
Radeon® X850 XT PE - 540/590 - 16 pixel pipelines
Part of this table is taken from ATIs website here: ati.amd.com/products/radeonx800/radeonx800series/index & here ati.amd.com/products/radeonx850/radeonx850series/index
Unfortunately what the original tables don't show is the number of pixel pipelines *. If you go to ATIs website 'product comparision' here: apps.ati.com/ATIcompare/ and tick X800XL & X800 Pro, you'll see the pixel pipeline numbers are listed. Note the memory speeds shown are the actual MHz & not the DDR equivalent rating, which is double.
At the moment their seem to be quite a few 'X800XT's being offered for sale which are not at the correct clock speeds. A common example being speeds of 400/700(=350MHz).
For starters the GPU speed of 400MHz is 100MHz below an XT. In other words it is 20% slower than what an XT should be and is in fact the rated speed for an XL! However the worst part is the memory speed, 700DDR =350MHz. That's a whopping 30% slower than the XTs!
These cards are really X800s (not Pro ,XL or XT), with 16 pipes and not the standard 12 pipes of the plain X800 (which would be great if they were sold as X800s), or at best they are XLs with cheap (crippled) memory.
Now that doesn't make them worthless, just as long as you understand these will perform no where near as well as a real X800XT ,and the price should reflect the reduced performance.
Oh and of course these shouldn't be sold as X800XTs at all. A vendor I discussed this with tells me the bios boot-up screen shows the card as an XT model, assuming this to be true then the actual graphics card maker is 'mislabelling' them. I'm surprised that ATI have let them do this especially with that large a discrepancy in clock speeds!.......
For a much more in depth GPU table look here, techpowerup.com/gpudb/
*To fully explain pixel pipelines is beyond the scope of my guide, but it is a crucial part of the GPU (ok ATI call it VPU ;) ).Given equal clock speeds a 16-pipe VPU is up to 33% faster than a 12-pipe VPU.
I say 'up to' because many other factors (limitations) come into play when running games which may not show up the differences as much.However the main point is that those 4 extra pipes make a significant difference to performance.
To give you an idea I've unlocked a couple of X800 GTOs in the past from 12-pipes to 16-pipes (via a vid bios flash) and performance gains were in the region of 15-25% without altering clock speeds.Looking at this review, tomshardware.co.uk/2005/11/25/donuk/page11 ,the more demanding games do show about a 33% increase in performance going from 12 to 16 pipes.
For information on converting (some) X800 GTOs & X800 Pro VIVOs to X800XL/XTs go here techpowerup.com/articles/overclocking/vidcard/127 and here techpowerup.com/articles/overclocking/vidcard/100 .
One other thing; before you shell out loads more cash on an X850XT PE over an X800XT PE, bear in mind that it is only about 5% faster! , and that the X800XT PE is only about 5% faster than the X800XT. Compare the 850s to the 800s in the above links to see what I mean. For some benchmarks look here anandtech.com/video/ and here tomshardware.co.uk/
Good luck on your hunt for an X800!