Performance at equal clocksBefore moving on to the tests of the models on the market we naturally wanted to check performance at equal clocks so as to measure the IPC gains announced in practice. To do so we overclocked a Core i7-2600K and a Core i7-3770K to 4.5 GHz on a DZ77GA-70K motherboard. They come with 2x4 GB of DDR3-1600 9-9-9.
There’s an average gain of 3.7% at equal clocks. Some applications are significantly faster, with for example a 7.7% difference in Adobe Lightroom, 6.8% in x264 and 6.1% in Bibble. In contrast, there’s only a 0.6% gain in Fritz Chess, 1.3% in Visual Studio 2010 and 1.7% in WinRAR.
In games the average gain is 2.8%, but Crysis 2 is apparently limited by the GPU. If we discount Crysis 2, the average goes up to 3.2% with just 1.2% better in F1 2011 but 5.9% in Starcraft II. As you’ll have understood, as a ‘Tick’ at equal clocks Ivy Bridge doesn’t produce anything dramatic in terms of IPC. Sandy Bridge was itself already very good in terms of efficiency!
What about DDR3-2133?
For this test G.Skill supplied us with a 16 GB kit of DDR3-2400 RipjawZ certified at 11-11-11 at 1.65v.
Unfortunately, this mode wouldn’t run on the DZ77GA-70K motherboard, but we did run our test suite on Ivy Bridge, still at 4.5 GHz with DDR3 2133 10-10-10 so as to show you the gains this gives compared to standard DDR3-1600 9-9-9.
We started with a memory latency reading in AIDA64 and the multithreaded bandwidth in the RightMark Multi-Threaded Memory Test:
- Latency: 33.7ns instead of 39.3ns
- Reads: 30.67 GB/s in place of 23.52 GB/s
- Writes: 29.14 GB/s in place of 22.37 GB/s
What does this translate to in practice?
The average gain with applications was 3.7% … the same as that provided by Ivy Bridge over Sandy Bridge! Three applications pulled this figure upwards significantly: 7-zip with +13.8%, Lightroom with +11.4% and WinRAR with a gain of 7.1%. In eight other cases the gain was under 2%.
The average gain in games was 5.7% and there was even a gain in Crysis 2, which is rather surprising given that it was limited by the GPU. Starcraft 2 responds best to the memory clock increase with a gain of 7.7%.
With RAM being very affordable at the moment, acquiring a faster kit shouldn’t therefore be completely excluded. A DDR3-2133 kit is around 50% more expensive than a DDR3-1600 one, but for 8 GB the difference is only around €25!
PCI Express 3.0
Our last test on this page concerns PCI Express 3.0 performance. We compared the performance obtained with PCI Express 3.0 x16 and PCI Express 2.0 x16 with a Radeon HD 7950 to take the readings, in non-paged pool mode to push the interface and controller to a maximum.
A good surprise as theoretical performance was doubled going from 2.0 to 3.0. There’s a particularly marked gain from the CPU to the GPU where we were at 9.2 GB/s on Sandby Bridge-E (see our test here
). Performances between Sandy Bridge and Ivy Bridge were the same in 2.0 x16 mode. Note however that such bandwidth isn't really exploited as yet, as noted in this article