Pixel Pipelines?

patriko · 08-30-2005, 09:21 AM

What is the importance of Pixel Pipelines when choosing a video card? I'm trying to decide between these two:

ATI Radeon X800XL and Sapphire Radeon X800PRO

The X800PRO seems to out-do the X800XL in all aspects (clock speed, etc.), but it has only 12 pixel pipelines. The XL has 16 pixel pipelines. Will I see that big of a difference? What do they do anyway?

Sorry for asking such a dumb question!
Patriko

Compumaniac12 · 08-30-2005, 01:28 PM

its hard to say i belive the xl is better, my card only has 4 pixel pipelines and it performs better then many that have 8. 12vs16 may be a slight change in performance, but with any x800 you will get good grapics for sure.
the easy way to tell, which ever costs more will likely perform better without any modding.

**keymaker** · 08-30-2005, 01:30 PM

someone correct me im wrong but i believe the more pixel pipeline on a videocard, the more frame rates it can render. i could be wrong so someone who knows alot more shed some light.

**UncleMacro** · 08-30-2005, 06:43 PM

Old games used to draw a pixel by taking a texture map, applying a simple lighting map, and then writing it to the frame buffer. The computation was quite simple. Recent games do a fairly complex computation for each pixel. The pixel may have lighting from multiple light sources, shadowing, bump maps, and various other effects computations which need to be done. The pixel pipes have to do that computation for each pixel individually. More pixel pipes mean that the video card can do more pixel computations. There's also the vertex pipes which do computations which affect the position of vertices. Most current games are limited by the pixel pipes rather than the vertex pipes. So for most recent games it's pixel shader power which is most important followed by memory bandwidth followed by vertex shader power. This page shows a comparison of the specifics of the ATI graphics chips. You should really read comparisons of the cards running real games because the fill rate and memory bandwidth are just theoretical maximums and not actual performance.

The X800XL is definitely quicker but it's not just a matter of the number of pixel pipes. The X800XL has 16 pixel pipes running at 400MHz and the X800Pro has 12 pixel pipes running at 475MHz. So the direct comparison is 16*400 versus 12*475. So it's actually 6400 versus 5700 when comparing the pixel shaders. An X800XL is roughly 10% quicker than an X800Pro.

patriko · 09-01-2005, 05:51 AM

Thank you for all the replies! I ended up getting the X800XL (if only for the slight performance upgrade, I saw the o/c'd benchmark stats and they're killer). Thanks again :-).

08-30-2005, 09:21 AM	#1 (permalink)
patriko Registered User Join Date: Aug 2005 Posts: 2 OS: Windows XP 32-bit	Pixel Pipelines? What is the importance of Pixel Pipelines when choosing a video card? I'm trying to decide between these two: ATI Radeon X800XL and Sapphire Radeon X800PRO The X800PRO seems to out-do the X800XL in all aspects (clock speed, etc.), but it has only 12 pixel pipelines. The XL has 16 pixel pipelines. Will I see that big of a difference? What do they do anyway? Sorry for asking such a dumb question! Patriko

08-30-2005, 01:30 PM	#3 (permalink)
keymaker Join Date: Jul 2005 Posts: 1,154 OS: windows xp	someone correct me im wrong but i believe the more pixel pipeline on a videocard, the more frame rates it can render. i could be wrong so someone who knows alot more shed some light. __________________ AVG Spybot SpywareBlaster Adware CCleaner Diskeeper ZoneAlarm

08-30-2005, 01:28 PM	#2 (permalink)
Compumaniac12 Registered User Join Date: Jun 2005 Location: Rochester, NY Posts: 209 OS: XP home sp1	its hard to say i belive the xl is better, my card only has 4 pixel pipelines and it performs better then many that have 8. 12vs16 may be a slight change in performance, but with any x800 you will get good grapics for sure. the easy way to tell, which ever costs more will likely perform better without any modding.

08-30-2005, 06:43 PM	#4 (permalink)
UncleMacro TSF Enthusiast Join Date: Jan 2005 Location: San Diego Posts: 2,133 OS: Vista SP1 My System	Old games used to draw a pixel by taking a texture map, applying a simple lighting map, and then writing it to the frame buffer. The computation was quite simple. Recent games do a fairly complex computation for each pixel. The pixel may have lighting from multiple light sources, shadowing, bump maps, and various other effects computations which need to be done. The pixel pipes have to do that computation for each pixel individually. More pixel pipes mean that the video card can do more pixel computations. There's also the vertex pipes which do computations which affect the position of vertices. Most current games are limited by the pixel pipes rather than the vertex pipes. So for most recent games it's pixel shader power which is most important followed by memory bandwidth followed by vertex shader power. This page shows a comparison of the specifics of the ATI graphics chips. You should really read comparisons of the cards running real games because the fill rate and memory bandwidth are just theoretical maximums and not actual performance. The X800XL is definitely quicker but it's not just a matter of the number of pixel pipes. The X800XL has 16 pixel pipes running at 400MHz and the X800Pro has 12 pixel pipes running at 475MHz. So the direct comparison is 16400 versus 12475. So it's actually 6400 versus 5700 when comparing the pixel shaders. An X800XL is roughly 10% quicker than an X800Pro.

09-01-2005, 05:51 AM	#5 (permalink)
patriko Registered User Join Date: Aug 2005 Posts: 2 OS: Windows XP 32-bit	Thank you for all the replies! I ended up getting the X800XL (if only for the slight performance upgrade, I saw the o/c'd benchmark stats and they're killer). Thanks again :-).