Although the steamroller cores in AMD's A8-7600 APU based on Kaveri significantly increased CPU efficiency, the company seemed to focus mainly on gaming performance with the update from last month. The A8-7600 wasn't much faster than last year's A10-6800K, but it was fast enough to run modern titles like BioShock Infinite and Tomb Raider without the help of a discrete graphics card.
At the same time that AMD has kept its promise of single-chip PC games for years, its efforts for cross-firing integrated graphics with discrete graphics are finally maturing. The company already advertised “Dual Graphics” in 2011 with its first Lynx-based APUs. However, due to Crossfire's poor frame time performance, it was largely rejected. This was also the case with the Virgo / Trinity APUs from 2012.
When the Richland APUs landed in 2013, AMD was working to improve frame stimulation performance through driver updates. With the arrival of Kaveri, we see solid Crossfire performance that is not affected by frame deletion and chopping. In this case, we took the time to do some dual graphics testing with the A10-7850K, the company's current flagship APU.
Currently, Kaveri APUs can only be paired with one of two discrete GPUs: the Radeon R7 240 and the R7 250. Both are cards under $ 100 that gamers wouldn't normally invest in, but in combination with them On-A10-7850K We noticed a performance on the GPU that has a greater impact on value-based builders.
AMD's R7 GPU
The A10-7850K is a quad-core part that works at 3.7 GHz and a turbo frequency of 4.0 GHz and has a TDP of 95 W. Confusingly, there are two models of the R7, both of which are clearly referred to as the R7. The A10-7850K has the full version with eight GCN processing units (each with 64 stream cores) for a total of 512 SPUs. The A10-7800 is the only other APU with the full R7, and this 65 W TPD part operates at 3.5 GHz and a turbo frequency of 3.9 GHz.
At this point, you will find a 385 SPU version on all other APUs, including the previously tested A10-7700 and A8-7600.
With 33% more SPUs, we expect the gaming performance of the A10-7800 to be noticeably better than when testing the A8-7600.
There is a large selection of discrete R7 GPUs, including 240, 250, 260 and 260X. The dual graphics function of the Kaveri APUs only works with the R7 240 and R7 250.
The R7 240 costs $ 70, has only 320 SPUs, and is available in the DDR3 and GDDR5 models. The prices do not seem to differ between the two types of storage. So when you buy an R7 240, make sure it's the GDDR5 version, although there aren't many of them.
This is a big deal because the DDR3 model is limited to only 28.8 GB / s memory bandwidth, while the GDDR5 model has more than double the available memory bandwidth at 72 GB / s.
The R7 240 core is clocked at 730 MHz – similar to the 720 MHz frequency of the R7 on the chip – and the GDDR5 version has a memory clocked at 1125 MHz for an effective speed of 4.5 GHz.
The price of the R7 250 rises slightly to $ 80 or $ 90 (there are also DDR3 and GDDR5 models. Fortunately, most models are equipped with the much faster GDDR5 memory this time, and the HIS model with which we test is one of them. The R7 250 is clocked much higher at 1000 MHz, while the GDDR5 memory is a whisker faster at 4.6 GHz.
This time we have to work with 384 SPUs, which is the same amount as the A8-7600, but less than the A10-7850K. There were rumors of an upcoming Radeon R7 255 with 512 SPUs (matching the A10-7850K), but at this point it is still speculation. We've also heard of the R7 250X, but it has the same 640 SPUs as the HD 7770. It's not clear whether the rumored R7 255 or R7 250X support dual graphics with the Kaveri APUs.