Memory subsystem performance
Before diving into our gaming and application tests, we'll take a moment to look a handful of lower-level metrics, starting with memory subsystem performance. Keep in mind that only the A8-7600 and the Intel CPUs are running their memory at 2133 MT/s. The A10-6700T config has a slower 1866 MT/s memory speed, and the A8-6500T is limited to 1600 MT/s.
The A8-7600 is a fair bit faster than its Richland-based siblings in our Stream memory bandwidth test. That's to be expected given the Kaveri chip's higher clock speeds, especially versus the A8-6500T. The A10-6700 is a closer match for the A8-7600, but it can't keep up, either.
While Kaveri looks fast versus Richland, it lags well behind the Haswell competition. The Core i3-4330 wrings much higher bandwidth from the same memory setup as the A8-7600.
Dialing back the A8-7600's thermal envelope has only a minimal impact on memory bandwidth, at least in this test. Let's see what Sandra has to say.
This multithreaded test measures the bandwidth of all caches on all cores concurrently. The different block sizes step us down from the L1 and L2 caches into L3 and main memory. Notice how the A8-7600's performance starts to fall off after 64KB, when the test spills out of the L1 cache, and after 4MB, when it exceeds the capacity of the L2 cache and pushes into system memory. Neither Kaveri nor Richland has an integrated L3 cache, so the test hits main memory when it runs out of L2.
The A8-7600 has higher cache bandwidth than the Richland chips we tested. The Core i3-4330 delivers substantially higher throughput than the A8-7600 at smaller block sizes, though. Those two chips are closely matched from 128KB through 512KB, but the Core i3 slows down as larger block sizes push into its L3 cache. The A8-7600's larger L2 cache has an edge until the caches are exhausted and the test becomes bound by the system memory interface.
The Core i7-4770K runs away with this test thanks to a combination of higher clock speeds, greater L1 and L2 cache capacity (via additional cores), and a larger L3 cache. Remember that it's not a direct competitor to the A8-7600 or any of the other contenders.
Next, we'll look at Sandra's cache and memory latency test. We used the "in-page random" access pattern to reduce the impact of prefetchers on our measurements. You can read more about this test right here.
Again, the results expose the cache configurations of each chip. This test is single-threaded, so the presence of additional CPU cores doesn't affect the results. The Core i7-4770K has lower access latencies than the i3-4330 only because of the difference in L3 cache size.
All of the AMD chips perform comparably until the 4MB block size. Starting at that point, the A8-7600 configs exhibit higher latencies than the A10-6700T and A8-6500T. The looser timings required by the A8-7600's 2133 MT/s memory could explain the difference.
Some quick synthetic math tests
AIDA64 has a collection of synthetic CPU benchmarks, some of which take advantage of the new instructions supported by the latest AMD and Intel CPUs. If you're curious, this page has details on each test. The CPU PhotoWorxx and Hash tests both employ AVX2 and XOP instructions. So do the FPU Julia and Mandel tests, which also support FMA4 code.
The A8-7600 can't catch its Core i3 competition in the PhotoWorxx test, and it's way behind in the two FPU tests. The chip outpaces the Intel duallie in the CPU Hash test, though. That test uses the SHA1 algorithm and runs much faster on Kaveri than it does on Richland. Of course, the A8-7600 also has higher CPU and memory clocks than the A10-6700T and A8-6500T. The tight race between those Richland chips suggests memory bandwidth isn't a major constraint in the CPU Hash test.
Given the different CPU and memory frequencies of our APU configs, it's difficult to get a sense of Kaveri's IPC improvements over Richland. We may have to revisit that topic with more targeted testing in the future. Given the timeline for this review, we elected to spend more time testing actual games and applications. Speaking of which, let's see how Kaveri's GCN-derived Radeon handles cutting-edge DirectX 11 titles.
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