X1800XL v 7800GTX: My personal review

[Madellga]

You can't see shimmering in screenshots. It happens when moving.
It has to do with the implementation for AF.

Derek (AT) mentioned something about this here:
http://www.anandtech.com/video/showdoc.aspx?i=2552&p=5

There were some recent threads about this.

Check out recent threads:
http://forums.anandtech.com/messageview...atid=31&threadid=1717671&enterthread=y

http://forums.anandtech.com/messageview...atid=31&threadid=1679570&enterthread=y

http://forums.anandtech.com/messageview...atid=31&threadid=1671561&enterthread=y

 

[CP5670]

Very interesting. So are the latest generation cards from both companies actually a step backwards in IQ? I can see a little bit of this shimmering in some games on a 6800 GT, but it mostly goes away if I use HQ mode. (although I can really notice it in one older game, Deus Ex, where 8x AF on quality mode actually looks worse than no AF; HQ pretty much fixes it but that drops the fps a bit)

 

[Munky]

Anyone else with a x1800 card want to comment on the shimmering? I hope there's a driver fix for this, or else we all might as well just buy a 7800gtx and suffer the shimmering for $100 less.

 

[xtknight]

Interesting...thanks.

 

[johnnqq]

this generation sucks

 

[Pete]

Thanks for the great post, Madellga.

FYI, AFAIK shimmering is caused by MIP-map (read: bri/try-linear) or LOD (lower makes textures appear sharper in screenshots but shimmers in motion) shortcuts, not necessarily AF shortcuts (which is just the obvious angle-dependency, simply less AF at some angles [resulting in blurrier textures, which usually means less shimmer]).

OT: C++G, trolling is bad enough, but preemptive trolling? Let's not fan the flames in such a helpful thread.

 

[Wreckage]

Not too surprising. Shimmering has been a problem from both companies recently and may have more to do with game implementations and driver tweaks than the actual cards themselves. The noise is also not a surprise, given the size of the cooler. Hopefully there will be an easy replacement for the fans (I replaced the fan on my Shuttle XPC because of noise). I don't think this generation of ATI cards is competing well, hopefully the R580 will come out with a single slot design that runs cool and quiet while still competing.

 

[Mize]

Ouch. I've been holding out for the XT ever since I saw Brent's filtering comparison to the GTX at hardocp. I'm a complete IQ junkie who will suffer 30 fps over texture aliasing any day. Are you certain that AF was at 16x and Quality mode?

If you still have the card, please test!

 

[DarkColonel]

what's shimmering?

 

[nRollo]

Good post Madellga. There are definitely strange things afoot in the image quality department.

First Keysplayer posts screenshots that show much better AF on a 7800 than HardOCP showed, now you tell us ATI shimmers more than nVidia.

If you're right and some web reviewers replicate your findings, it will be sad days for ATI- they've pretty much been marketed on the better image quality angle.

You should post this at Rage3d, there are probably a ton of guys there waiting for XLs/XTs who might want to know this. (that shimmering is a very big deal to some)

 

[Pete]

Madellga, if you still have the XL, would you mind trying it in WoW, but with Catalyst AI disabled? If that doesn't fix the shimmering, could you download ATI Tray Tools from Guru3D and see if disabling Trilinear Optimizations does anything? Finally, you could try disabling Aniso Optimizations.

DC, AFAIK, shimmering (aka sparkling, aka pixel popping) is due to under-filtered textures. So, when you move the camera and the texture under a screen pixel changes, if the underlying texture is too contrasty or under-filtered, the pixel may shimmer/sparkle/pop from, say, a white color to a black one, rather than from a light to a dark gray. Less filtering means faster performance because it requires less memory access. (I hope I'm not too wrong on this point.)

 

[HeroOfPellinor]

Your X1800XL is obviously an NVidia fanboy.

 

[Kalessian]

I thought the 1800 line had a special AF mode that totally turned off optimizations? I remember seeing a picture of it being used and being impressed.

 

[Madellga]

Originally posted by: Kalessian
I thought the 1800 line had a special AF mode that totally turned off optimizations? I remember seeing a picture of it being used and being impressed.

Yes, I used that too. As I explained, I tried:
a) Default settings (application controlled);
b) All maxed for Quality (driver controlled);

I don't recall the name, but there is a check box on the AF screen.

 

[Madellga]

Originally posted by: Pete
Madellga, if you still have the XL, would you mind trying it in WoW, but with Catalyst AI disabled? If that doesn't fix the shimmering, could you download ATI Tray Tools from Guru3D and see if disabling Trilinear Optimizations does anything? Finally, you could try disabling Aniso Optimizations.

DC, AFAIK, shimmering (aka sparkling, aka pixel popping) is due to under-filtered textures. So, when you move the camera and the texture under a screen pixel changes, if the underlying texture is too contrasty or under-filtered, the pixel may shimmer/sparkle/pop from, say, a white color to a black one, rather than from a light to a dark gray. Less filtering means faster performance because it requires less memory access. (I hope I'm not too wrong on this point.)

Pete, I will return the card on Saturday morning. It is bed time for me now. I will try it tomorrow.
I used a special version from Atitool, made for the X1K - my focus was to watch and control the fan/speed/temperature. But I didn't tweak the settings there.

I am pretty sure I disabled everything in the driver, as mentioned before I first tried Default settings (application controlled) and maxed out the quality at World of Warcraft.

I also tried later using all HQ options, similar results.

I will also try on different places. The ones that I find worse are: Sepulcher and Mulgore.

Any other suggestions? I will try to accomodate if possible/feasible.

 

[Madellga]

Originally posted by: Rollo
Good post Madellga. There are definitely strange things afoot in the image quality department.

First Keysplayer posts screenshots that show much better AF on a 7800 than HardOCP showed, now you tell us ATI shimmers more than nVidia.

If you're right and some web reviewers replicate your findings, it will be sad days for ATI- they've pretty much been marketed on the better image quality angle.

You should post this at Rage3d, there are probably a ton of guys there waiting for XLs/XTs who might want to know this. (that shimmering is a very big deal to some)

Thanks Rollo. I wish other reviews could prove me wrong

I really wanted a card that would be fast and have good IQ - including shimmering. With current processing power, that was supposed to be the case nowadays.

Computer stuff is a Hobby for me - I am no IT expert like Anand's gang. Although I'm doing this since the early PC days, it is possible I missed something here.

I appreciate your suggestion and I will post tomorrow at Rage3d. I think I had an account there, but I don't remember the password (and changed ISP). I will have to create a new one. They might think I am a Nvidia fan trolling.....:evil:

 

[Pete]

Those two options (Catalyst AI and Trilinear Optimizations) are the ones I believe are most likely to affect shimmering. (Well, there's also LOD, but I don't know how to affect that other than maybe setting both Texture and MIP-map Preference sliders to High Quality, which you probably already did, or were the default 'Balanced' CP/CCC settings.) If you can change the CatAI and Tri Opts specifically (individually and together)--via either ATT or ATI's CCC or CP--I'm sure we'd all appreciate it.

The reason I think this is a MIP-map (trilinear) optimization is b/c the 9800 doesn't have the hardware to support ATI's "trylinear," while the X800 does and probably so does the X1800.

The HQ setting for AF simply removes angle dependence, AFAIK. I don't think it will affect shimmer (at least, not what you're seeing), just texture clarity, but it probably doesn't hurt to use it. Well, it shouldn't hurt IQ, but it may impact framerate a tiny bit.

 

[Madellga]

Originally posted by: Mize

Ouch. I've been holding out for the XT ever since I saw Brent's filtering comparison to the GTX at hardocp. I'm a complete IQ junkie who will suffer 30 fps over texture aliasing any day. Are you certain that AF was at 16x and Quality mode?

If you still have the card, please test!

I normally play at 4AA 8AF. When I saw the shimmering on the X1800XL, I bumped the AF to 16, but no improvement

I was not doing screenshots and comparing texture quality. I was interested on the shimmering only.

With the 7800GTX, HQ and Clamp, it is (in comparison to the X1800) visible but somewhat limited small areas on the floor or landscape (WoW). I have yet to check the shimmering with 3DMark05.

With the 1800XL, HQ and AF (no optim.), it was very noticeable and spread over the ground and landscape. I saw shimmering also on the 3DMark05 run.

There is a chance that this is a driver issue and could be fixed, just like Nvidia did with the 78.03 beta.

Let's hope for it....

 

[orwell1984]

I was all worked up about shimmer when I got my 7800GTX. I looked extra hard for shimmer and found it. I was sure that there was shimmering I didn't have with my 9800 pro. But after benching all my games with my 9800pro again, I realised there was very similar shimmering. In a few cases, shimmering with the 9800 pro was less apparent, but still there and in the same places. I never did get the kind of texture shimmering that I saw in vid clips meant to illustrate it. Also the IQ improvement going from my 9800 pro has been quite impressive. I have read a few reviews on IQ and found that staring at images of chain link fences does not give me a clear idea of who has better IQ.

My conclusion is that both cards are quite good and preferences for one or another are very subjective. I bought the 7800GTX because it was available and am quite pleased. If somehow things had been different and had ended up with a x1800xt, I don't think I would have been significantly more or less pleased. BTW, I play flight sims and the 2 I play the most often have a slight edge with the 7800GTX.

Thanks for the post. I have wanted exactly the info you have given.

Cheers.

 

[aggressor]

Just to chip in, I had an X800XL and there was no shimmering which was very apparent on my 6800GT (which was returned) and my new 7800GTX. I guess this just started with the X1800 line. It's a shame, because it was one of the very few reasons I was thinking of spending a little more on an ATI card...now, definitely not.

 

[fierydemise]

I'd like to hear if this is an isolated incident or a common occurance, I know a fair number of peopls have 1800XLs, so will those who have them tell us if you can or have seen it.

 

[nRollo]

Originally posted by: Madellga
I appreciate your suggestion and I will post tomorrow at Rage3d. I think I had an account there, but I don't remember the password (and changed ISP). I will have to create a new one. They might think I am a Nvidia fan trolling.....:evil:

I think if you tell them you could care less whose video card you own, and that you were hoping the shimmer would be better on the ATI, they'll listen.

Like I said, to some people that shimmer issue is a big deal, and those people would probably be fairly angry if they bought the card and had the shimmering. Others who have it might confirm or deny your findings, and lend suggestions on how to alleviate the problem.

Either way, the truth will be got to and everybody wins. (IMO this is what the boards are all about- exchange of user information)

 

[5150Joker]

Problem is that with LOD clamp you actually reset mipmap level back to 0. The XT HQ AF allows for trilinear filtering on all stages so if you are seeing shimmering, it's not the cards fault but rather the game for setting a negative LOD. If you want to do a fair comparison, turn off the clamp on the 7800 GTX and run both cards on HQ AF. Otherwise having one card's drivers reset the LOD isn't a fair comparison.

Anyhow the OPs post was very subjective since it picked a game that may just be setting a negative LOD and causing shimmering to occur on ATi cards because their drivers lack the same clamp nVidia has needed to lessen shimmering in other games. I don't think anyone can really dispute that angle-independent AF is superior to angle-dependent AF. Bottom line is that nVidia cards like the G70 can't even match the R420 series in angle-dependent AF (ATi trylinear looks better) let alone R520. I say this with the most utmost unbiased opinion. I've got to give credit where it's due and in this case ATi beats nVidia.

Man you guys are tempting me to go out to my local Frys and pick up an R520 to prove this thread wrong. I think I might just do that this coming weekend (pending wife approval) and post some uncompressed vids to show that even ATi trylinear is superior to nVidia AF.

P.S. I may have some old FRAPs vids laying around on one of my HDs where I compared 6800 AF vs X800 AF and the X800 was clearly superior. Since G70 AF has been shown to be worse than the 6800 AF it should drive my point home.

 

[Blastman]

This doesn?t make much sense. The X1800?s have the same AF routine as the previous cards X800?s. And there has been no perceptible difference reported between the 9800?s and the current generation of cards from ATI.

Originally posted by: Madellga
I went back to the GTX and although the shimmering is there at HQ / Clamp (81.85), it was barely noticeable in comparison to the X1800XL. ?

If a clamp is helping shimmering, then that likely means there is a -ve LOD bias in the game-- ATI has no clamp for this as it is generally assumed that developers won?t be doing this. AFAIK very few games use a -ve LOD bias so the problem would be far and few between.

The problem is that on NV cards, they are under-sampling the MIPS (at least in only Q mode, and maybe soemwhat in HQ mode too), so you will get shimmering in many games that don?t have a -ve LOD bias, and there will be no fix using the clamp.

 

[CaiNaM]

it's nice to get some feedback from someone who personally has a card in their hands.. what's funny tho is that this was posted over a month ago on these forums and was for the most part blown off....