Performance Summary Diagrams
Here is a table with full test results, so we can proceed to our summary charts.
First of all, we want to see the difference between Radeon HD 7790s with 1 and 2 gigabytes of onboard memory, the 1GB version serving as a baseline:
The Radeon HD 7790 can really benefit from an extra gigabyte of memory. The 2GB version is almost twice as fast in Company of Heroes, 15% faster in Tomb Raider and 7% faster in Total War: Shogun 2 - Fall of the Samurai and Crysis 3. The Fire Strike Extreme scene from 3DMark (2013) may also be mentioned. Still, we don’t think that this inconsistent performance boost is worth the $40 difference in price we see between the two versions. Moreover, in those cases where we see the difference in speed, the frame rate is anyway too low for comfortable play.
The next diagram shows the efficiency of the CrossFireX technology as applied to two 1GB Radeon HD 7790s in terms of average frame rate.
The CrossFireX tandem is much faster in every game, save for Company of Heroes 2: by an average 80% without antialiasing and by an average 82% with antialiasing. Unfortunately, the bottom speed doesn’t grow up proportionally.
The last diagram helps us compare the Radeon HD 7790 CrossFireX configuration with a single factory-overclocked GeForce GTX 760.
The two Radeon HD 7790s are often faster than the single GeForce GTX 760 and even much faster in two games (GRID 2 and Tomb Raider without SSAA). In its turn, the GeForce GTX 760 is superior in Company of Heroes 2 because the CrossFireX technology failed to work in that game. Anyway, considering that both solutions cost the same money, we'd prefer the single GeForce GTX 760 which has no problems with bottom speed which plague the entry-level CrossFireX tandem.
We’ve tested five Radeon HD 7790 models today and find it hard to name an overall winner among them. The ASUS version is the quietest. The MSI has the most efficient cooler, overclocks well and is compact. The Gigabyte has 2 GB of graphics memory, even though their benefits are not so obvious. The Sapphire has the best accessories and packaging. The HIS version seems to be ordinary compared to the others, but it costs as much as a reference Radeon HD 7790 while being pre-overclocked to 1075/6400 MHz. Their GPUs are similar in terms of ASIC quality and don't differ much in overclocking potential (±20 MHz). As for memory overclocking, the MSI reached the best result (7120 MHz) while the ASUS and HIS had the worst result (6640 MHz). So, it’s really hard to say which one is better overall.
As for AMD’s multi-GPU technology, we don’t think it has any perspectives for entry-level graphics cards. And even if you really want to build a CrossFireX tandem out of two Radeon HD 7790s, you should take the 2GB version of the card. It may help you avoid problems with bottom speed. As for average frame rate, the efficiency of CrossFireX is quite high, so the multi-GPU technology proves its viability once again.