Does the 7900 series z-cull (?) cut out after 2048x1536?

[dug777]

http://www.tomshardware.com/2006/05/26/monarch_hornet_pro/page7.html

look at the hl2:lc and d3 benchies...

 

[Munky]

I dont know if it's the z-cull resolution limit or they're running out of video mem, or maybe it's something else. I see Doom3 takes a dive after 1600x1200, and I know these cards cover more than 1600x1200 for their z-culling algorithm.

 

[SonicIce]

Maybe it's because 25x16 has 2.13 times are many pixels as 16x12, and thats alot more work especially with AA. But then again, it's toms hardware.

 

[hemmy]

man Tom has true skill, they are running 4xAA and 8xAA at the same time!!! wow, breaking the rules!!!

I think it has a slight drop, but the R5xx series has double the z-buffer size as G7x cards

http://www.firingsquad.com/hardware/nvidia_geforce_7900_gx2_quad_sli/page6.asp

(quad sli preview, but they run very high quality settings)

 

[yhelothar]

It looks like the bench was limited by the CPU until it reached 2048x1536, in which the video card became the limiting factor.

 

[Shadowmage]

It's z-cull... you're right

 

[BFG10K]

It looks like the bench was limited by the CPU until it reached 2048x1536, in which the video card became the limiting factor.

Agreed.

Without a Radeon of sorts to compare it's impossible to say if z-cull is the limiting factor or not.

 

[dug777]

Didn't this AT tell us what the z-cull on these babies while they were going through a crazy high res period when the 7800 series came out? I remember the x850xt and 6800U got hammered stepping up over 1600x1200, and both Nvidia and ATI increased their z-cull significantly, but i forget what to...

 

[otispunkmeyer]

i remember the 6800's used to take a dive after 1600x1200 too

 

[dug777]

ya.

 

[Wreckage]

Originally posted by: BFG10K

It looks like the bench was limited by the CPU until it reached 2048x1536, in which the video card became the limiting factor.

Agreed.

Without a Radeon of sorts to compare it's impossible to say if z-cull is the limiting factor or not.

http://www.techreport.com/etc/2005q3/hires-gaming/index.x?pg=1

The article is from last year but it explains a bit about this topic.

 

[dug777]

Originally posted by: Wreckage

Originally posted by: BFG10K

It looks like the bench was limited by the CPU until it reached 2048x1536, in which the video card became the limiting factor.

Agreed.

Without a Radeon of sorts to compare it's impossible to say if z-cull is the limiting factor or not.

http://www.techreport.com/etc/2005q3/hires-gaming/index.x?pg=1

The article is from last year but it explains a bit about this topic.

from what i can see i'm right then....

The 7800GTX was designed to deliver much higher raw performance at 2048x1536, and better performance scaling from 1600x1200 to 2048x1536.

 

[DeathReborn]

Originally posted by: dug777

Originally posted by: Wreckage

Originally posted by: BFG10K

It looks like the bench was limited by the CPU until it reached 2048x1536, in which the video card became the limiting factor.

Agreed.

Without a Radeon of sorts to compare it's impossible to say if z-cull is the limiting factor or not.

http://www.techreport.com/etc/2005q3/hires-gaming/index.x?pg=1

The article is from last year but it explains a bit about this topic.

from what i can see i'm right then....

The 7800GTX was designed to deliver much higher raw performance at 2048x1536, and better performance scaling from 1600x1200 to 2048x1536.

I read somewhere it was about a 30% improvement in the G70 architecture, i'll see if I can find the link again.

Edit: Here's the link that mentions improved z culling altho it doesn't state anything other than a 30% increase over NV40.
http://techreport.com/reviews/2005q2/geforce-7800gtx/index.x?pg=2

 

[BFG10K]

I remember the x850xt and 6800U got hammered stepping up over 1600x1200, and both Nvidia and ATI increased their z-cull significantly, but i forget what to...

The 6800U (NV4x) did, yeah, but the Tom's Hardware article you linked to doesn't even have an NV4x in the tests.

There are 2560x1600 benchmarks out there that show the 7900GTX trading blows with the X1900XT.

The article is from last year but it explains a bit about this topic.

It has nothing at all to do with the topic. It explains an NV4x loses performance at resolutions greater than 1600x1200 but again Tom's didn't test an NV4x, they tested a G71.

from what i can see i'm right then....

How are you right? The NV4x wasn't even used in Tom's tests and Tech Report state themselves the G70 (and ergo the G71) has no such limitation.

With Tom's results you can't make any inference on z-culling because there's no Radeon X1900XT to compare it to. From the benchmark results I think it's painfully obvious that the sharp performance drop is simply a result of CPU limited benchmarks becoming GPU limited.