nVidia 8xMSAA driver bug

[BFG10K]

In the past I noticed some 8xMSAA screenshots I took on my previous G80 card in certain games (e.g. HL2) had very poor image quality, lower than that of 4xAA in fact. Also several 16xQ screenshots I've seen in various online reviews also have very poor image quality (e.g. Anand?s GTX280 review).

Now it looks like we know the cause, and 16xQ is likely being affected too as 8xQ is the base multi-sampling level for that mode.

http://www.behardware.com/news/lire/19-09-2008/

Now before everyone gets too excited with the "OMG nVidia is cheating!?, benchmark scores appear to be unaffected (i.e. you get the performance hit of 8xQ, just not the IQ).

I noticed this problem many months ago, maybe even as far back as my 8800 GTS which I sold over a year go, so I hope this isn?t going to be another nVidia driver problem that takes years to fix.

 

[ViRGE]

Humm, I wonder when this was introduced? I could swear there were at least a couple of GTX280 reviews using the AA viewer, with nothing out of the ordinary.

 

[BFG10K]

Originally posted by: ViRGE
Humm, I wonder when this was introduced? I could swear there were at least a couple of GTX280 reviews using the AA viewer, with nothing out of the ordinary.

The problem only manifests itself if you're forcing AF through the control panel, which most reviewers don't do.

I however do this and like I said earlier I have a sneaking suspicion this has been around for at least a year, if not longer, based on my ad-hoc testing of 8xQ and 16xQ screenshots.

As for a documented example: http://www.anandtech.com/video/showdoc.aspx?i=3341&p=11

Look at the 16xQ screenshot (bottom-right result); it looks works than 4xAA. There is no possible way that could be the case given the far higher sample count of that mode compared to 4xAA (8xMSAA + 8xCSAA vs 4xMSAA). They were probably forcing AF in the control panel when the 16xQ shot was taken.

Anand was using a GTX280 and Behardware was using a 8800 which means the issue probably affects all nVidia DX10 parts.

 

[apoppin]

Do you think that very few people pick up on the issue because just about everyone with G80 and above hardware uses CSAA and not 8x MSAA? Nvidia users have CSAA which is faster than 8x MSAA and pretty good visually.

 

[BFG10K]

Originally posted by: apoppin

Do you think that very few people pick up on the issue because just about everyone with G80 and above hardware uses CSAA and not 8x MSAA? .

I personally think it wasn't noticed because most people don't generally run above 4xAA, if they even run AA at all that is.

 

[Modular]

Good find. There are certain games that simply need AA. BF2 was the first one I played where I couldn't stand not having some form of it enabled. Remember how terrible the power lines looked in that game w/o AA?

 

[apoppin]

Originally posted by: BFG10K

Originally posted by: apoppin

Do you think that very few people pick up on the issue because just about everyone with G80 and above hardware uses CSAA and not 8x MSAA? .

I personally think it wasn't noticed because most people don't generally run above 4xAA, if they even run AA at all that is.

What excuse do the reviewers have?
- mostly they missed it although they do run it 😛

good find!!
- i tend not to force anything in the CP

 

[BFG10K]

Originally posted by: apoppin

What excuse do the reviewers have?
- mostly they missed it although they do run it 😛

Well to be fair this would be very hard to spot as you have to force AF through the control panel (which most reviewers don't do) and even when you do the performance hit is in line with 8xMSAA so it doesn't raise any red flags.

I spotted something was amiss because I just happened to be comparing my own 8xQ screenshots but I still didn?t have the whole picture until I saw the article.