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Deeper with the GeForce 7 Series - Part 2

PCI Express x16 graphics cards
Chipset GeForce 7800GT / 7800GTX 256 MB, 256 bit

This article is actually meant more as an addendum to the first part (which you can read here), where we talk mostly about transparency antialiasing performance from NVIDIA's GeForce 7 series cards. For the most part, transparency antialiasing is only really usable on old games (that does use lots of transparent textures). Newer games tend to be too much of a burden, even for the fastest GeForce 7800GTX, especially if we were to use 4x AA. We did mention that 2x AA seems to be the best compromise, but understandably image quality is not up to par to 4x AA. However, there's no way we can enabled 4x AA and 2x SSAA transparency antialiasing at the same time on the GeForce 7 series.

However, we didn't test 2xQ AA. So, in this article, we'll take another look at transparency antialiasing, particularly with 2xQ AA. From past experience, we did see that 2xQ can offer better image quality (meaning less aliasing) than 2x AA or even 4x AA (you can read the article here). So, it will be interesting to see whether or not that's true with transparent textures. After taking a look at image quality from these three modes, we also ran some performance test to see just what kind of frame rates in game we can expect with these modes.

From our suite of game benchmarks, only two games (Battlefield 2 and Serious Sam 2) exhibit both image quality and performance differences with transparency antialiasing. Both are FPS games, so we decided to look for games from other genres that made use of transparent textures for testing purposes. We chose three candidates - Age of Empires 3, Dungeon Siege 2 and Richard Burns Rally. Of the three, Richard Burns Rally responds well to transparency antialiasing the most, so we decided to enter this game to our benchmark suite. Both Age of Empires 2 and Dungeon Siege 2 does exhibit some quality improvements, but these games are very system limited, so we'll be using them as system benchmarks rather than graphics benchmarks.

Image Quality Comparison

First of, let's take a look at Serious Sam 2. Partly because of it's extensive use of transparent textures, this game will benefit the most from transparency antialiasing. On the other hand, it's also very taxing on performance. The screenshots are in this order: 4x SSAA, 2x SSAA and 2xQ SSAA.



If you look at the vines hanging off the tree, you can tell that both 4x and 2xQ is doing a better job than 2x. At the same time, if you look at the far palm tree on the left part of the image, both 4x and 2xQ also does a better job of removing aliasing - polygon wise). So, does 2xQ is the 'holy grail' of antialiasing? Not quite, if you look at the bottom of the palm tree, you can see 2xQ is still not up to par with 4x - the image still has some aliasing. You can see the same differences on both Sam's guns (the left one is more pronounced). Of course, the differences are hardly noticeable in gameplay.

Let's take a look at Battlefield 2. While 4x SSAA transparency antialiasing does incur quite a big hit with Battlefield 2, the penalty is mask by system limitations whey you're playing the game. So, you really can get away with 4x SSAA with this game. We chose a different scene for these shots, so you can tell antialiasing differences for both transparent textures and polygons.



Looks like 2xQ works even better than 4x in some parts. You can definitely still see jaggies on some of the leaves with 2x and 4x where 2xQ has less. And if you look at the power lines and the poles, you can see 2xQ does a pretty good job at removing aliasing, close or the same with 4x. But again, we can see that 2xQ still has some drawbacks - look closely at the roof of the building right in front. You can definitely see 4x doing a better job than 2x and 2xQ. These differences are minimal, but they can be noticeable in gameplay.

So, 2xQ does come pretty close to 4x AA quality. There are still differences, but you won't really notice them and the quality improvements are substantial to just 2x AA. The drawback is of course, you have to force 2xQ from the driver panel, since no game (that we know of) can make use of 2xQ from the in game menu. Forcing antialiasing mode can 'break' some games, particularly those with frame buffer effects (bloom for example).

Performance

Since we're focusing on transparency antialiasing, we only did tests with a small number of games - Age of Empires 3, Battlefield 2, Dungeon Siege 2 , Richard Burns Rally and Serious Sam 2. Since only Battlefield 2, Richard Burns Rally and Serious Sam 2 exhibit performance differences, we will only provide the results from these games. Our test setup remains the same. We tested three cards in total - a GeForce 7800GT, a standard clock GeForce 7800GTX and the ASUS EN7800GTX TOP 2xQ AA mode is forced through the driver panel, while 2x and 4x AA, when available, are set from the in game settings menu. For Richard Burns Rally, both AA and AF are forced from the driver panel. Image quality setting in the driver panel is set to High Quality for best image quality. We limit the tests to 1024 x 768, 32 bit. Higher resolutions should be pretty similar, 2x and 2xQ will be faster than 4x.

Our test setup
AMD Athlon 64 3500+ socket 939
2 x 256 MB Kingston KVR 3-3-3 PC3200 DDR-SDRAM
MSI K8N NForce 4 SLI motherboard
Maxtor DiamondMaxPlus9 80 GBs Serial ATA 8 MB buffer
ASUS E-616 DVD-ROM
450 watts ATX power supply

Windows XP Professional with Service Pack 2 installed
NVIDIA Forceware 81.95 reference driver
NVIDIA NForce 4 6.66 reference driver
Creative SoundBlaster Live! 24 bit 5.12.1.512 driver.
DirectX 9.0c

The results:

Just as expected, 2xQ performance is pretty much the same with 2x performance. Considering the quality is pretty close to 4x, that's quite an improvement. Those looking for the best image quality can still push 4x if you want, since even the 7800GT can still push high enough frame rates, with 40 fps minimum. Interesting to see we can gain pretty much the same rate by slightly overclocking the 7800GTX as we did by moving from the 7800GT to the 7800GTX.

	7800GTX TOP		7800GTX		7800GT
	4x	2xQ	4x	2xQ	4x	2xQ
<30 fps	0	0	0	0	0	0
30-45 fps	0	0	0	0	0	0
45-60 fps	0	0	0	0	5	0
60-90 fps	23	0	49	0	59	0
90-120 fps	41	16	15	21	0	47

Looking at the fps progress graph, we can see that the heaviest part of the benchmark is when we're racing through the pine forest. This is expected with transparency antialiasing, since that part is where transparent textures is at its heaviest. We can also see that we actually gain the most by switching to 2xQ with the 7800GTX. Looks like the 7800GTX TOP slightly higher clocked is much more needed with 4x AA, where the performance difference to the 7800GTX stays pretty much the same across the board..


No, that's not spaces you see above. Since we're using scores from FRAPS, we see a lower minimum frame rates in this game - mostly because of texture and data loading. Looks like even 2xQ is unusable with both the 7800GT and standard 7800GTX, with average frame rates just slightly above 30 fps. The 7800GTX fares slightly better, but not much. Let's take a look at the fps progress graph below before making any conclusions.

	7800GTX TOP		7800GTX		7800GT
	4x	2xQ	4x	2xQ	4x	2xQ
<30 fps	63	1	63	1	63	13
30-45 fps	0	37	0	61	0	50
45-60 fps	0	25	0	1	0	0
60-90 fps	0	0	0	0	0	0
90-120 fps	0	0	0	0	0	0

Ignoring the very first and very last part of the graph (where loading occurs), we all can see that only the 7800GTX TOP offers barely playable frame rates of 25 fps with 4x AA. Serious Sam 2 is just too heavy with transparency antialiasing for the GeForce 7 series (sans 7800GTX 512 MB). So, 2x and 2xQ is the only viable alternative with this game. With 2xQ, the 7800GT pretty much stays around the 30 fps mark, while the 7800GTX stays pretty much around 35 to 38 fps. The 7800GTX TOP offers more improvement, reaching over 40 fps in most parts. This does show why these slightly higher clocked cards are worth the extra bucks Unlike Richard Burns Rally, the 7800GTX TOP gains the most by switching to 2xQ here.


With bots and physics in play, we can see no performance difference between 4x, 2x and 2xQ AA in this game on all cards. While there are variations between results, these are 'normal' with Battlefield 2. To see any difference, we either have to use a faster processor such as the Athlon FX-55 or FX-57 or use a higher resolution. A higher resolution is cheaper, but if you read our last article, you'll see that even the 7800GT is fast enough with 4x SSAA transparency antialiasing at 1280 x 960. 2xQ should provide fast enough frame rates at 1600 x 1200 if you want to, but we recommend 4x SSAA at 1280 x 960 instead - frame rates are about the same with better image quality.

Conclusion:

Looks like 2xQ seems to be pretty much the most viable compromise between performance and quality with the GeForce 7 series. It offers performance levels virtually the same with 2x and quality near 4x. Even more so, since there's no way to get 4x AA and 2x SSAA for transparent textures enabled at the same time with the GeForce 7 series. There are differences, but we think it's worth the compromise. We recommend using 2xQ if you find 4x SSAA to be too slow for real world gameplay in the games you play.

Thankfully, that's only true for a handful of new games such as Serious Sam 2. Most games should be ok with 4x SSAA transparency antialiasing, frame rates are reasonably high enough. In this situation, you can and should enable 4x, since you'll get the most quality with a reasonably, slightly lower frame rates. If you prefer higher resolutions, 2xQ is the only way to go with a single card - you need at least two GeForce 7800GTX to enjoy 4x SSAA transparency antialiasing with high enough frame rates at all times at resolutions above 1024 x 768, 32 bit.

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