Direct3D 10: Vertex texture fetch rate

Vertex Texture Fetch tests measure the speed of many vertex texture fetches. These tests are essentially similar, and the correlation of their results in Earth and Waves tests must also be similar. Both tests use displacement mapping based on texture fetches. The only major difference is that the Waves test uses conditional branches, while the Earth test does not.

Let's analyze the first test (Earth) in Effect detail Low mode:

Judging by our previous reviews, this test is affected not only by texturing speed, but also by memory bandwidth. The easier the mode, the stronger its effect on performance. That's exactly what we see in our today's test results. Interestingly, changing modes in RADEON HD 3870 with reduced frequencies does not have such a strong effect as in case of HD 4670. Perhaps, the latter is limited by memory bandwidth to a greater degree.

Our Low-End card from AMD is the leader in all modes, although RADEON HD 3870 catches up with it in the heaviest mode. The card under review outperforms NVIDIA products in this test by 30-300% depending on a mode and card model. The difference from the previous model of the same price range (RADEON HD 3650) is less than twofold, which also shows that performance is limited by memory bandwidth. Let's have a look at results of this test with more texture lookups:

The situation has changed. HD 3870 demonstrates the best result now. And both GeForces roll back even lower, so it's not interesting to compare them with the new card from AMD -- this performance difference reaches 3-3.5 times. RADEON HD 4670 is outperformed by HD 3870 in the heaviest mode, still leading with a wide gap in the other modes. We've noticed this interesting peculiarity in our previous reviews -- as geometry complexity grows, performance differences between RV7xx and RV6xx grow smaller.

Let's have a look at results of the second vertex texture fetch test. The Waves test executes fewer texture lookups, but it uses conditional branches. The number of bilinear texture lookups in this case reaches 14 (Effect detail Low) or 24 (Effect detail High) per each vertex. Geometry complexity changes just like in the previous test.

The Waves test also shows the advantage of AMD cards in these price ranges. The new model from the RADEON HD 4600 series looks good, demonstrating results close to HD 3870 and outperforming both NVIDIA solutions. The heavier the mode, the more GeForce cards lag behind. Let's analyze the second modification of the test:

There are minimum changes, although AMD results grow even better versus NVIDIA performance as complexity grows. The latter again suffered from a bigger performance drop than AMD solutions. RADEON HD 4670 demonstrates the best results in all modes. It's a tad faster than HD 3870 owing to higher efficiency of texture lookups. Even HD 3650 outperforms GeForce 9500 GT and 8600 GTX in heavy modes -- AMD cards perform much better now in our vertex texture fetch tests than they used to.

Conclusions on synthetic tests

Synthetic tests of the new budget RADEON HD 4670 card, based on RV730, as well as other graphics cards from both chipmakers show us that the new Low-End solutions from AMD must also demonstrate relatively high results in games. This GPU belongs to the new RV7xx architecture, which features a lot of modifications. It is way faster in most synthetic tests than its counterparts of the previous generation, both from AMD and NVIDIA. The RV730-based card performs on a par or even better than prev-gen solutions of a higher level in many tests. We should thank the RV7xx architecture for that, it's apparently better than previous architectures from AMD.

Significant performance gains in RV7xx are obtained not only owing to increasing the number of execution units, but also due to effective architectural improvements relative to RV6xx. RV7xx solves the problems of previous GPUs, it contains more texture units, stronger TMUs and ROPs, plus other changes. As a result, this series has become much more efficient and better balanced. Features and performance of all important units are improved. So the new graphics cards of the RADEON HD 4600 series are an excellent choice even for modern games with high requirements to shader performance, complex texturing, and fill rate. RV730 and RV710 contain a lot of texture units even in comparison with RV770, and their results in real applications must be rather high.

The next part of our article traditionally contains tests of the new solution from AMD in modern games. Results in games should comply with our conclusions on synthetic tests, even taking into account that rendering speed in games depends more on memory bandwidth, texturing speed, and fill rate. So HD 4670 will not be so much faster as in some synthetic tests. However, the new solutions offer powerful TMUs and ROPs, so we can assume that average performance of HD 4670 in games will certainly exceed performance of the main competing products from NVIDIA. It will be close to the speed of RADEON HD 3850.

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