|MSI Z68A-GD80 Intel Motherboard|
|Reviews - Featured Reviews: Motherboards|
|Written by David Ramsey|
|Thursday, 02 June 2011|
Page 13 of 15
The Cougar Point/Sandy Bridge platform brings major changes to the overclocking process. Here are the bullet points:
Intel's new chipsets derive almost every clock on the motherboard from the base clock (BCLK) frequency. This makes board design simpler and more reliable, but it also means that raising the base clock raises other clocks on the system...like, say, the PCI-E slot clocks, the SATA clock, and so forth. What this means in practice is that you'll be lucky to raise the BCLK as much as 5MHz without crashing your system. An overclocking mechanism enthusiasts have used for more than a decade is consigned to the dust bin of history.
Intel compensates for this by giving all Sandy Bridge processors unlocked multipliers: K-series processors get "fully unlocked" multipliers with no limits, while non-K series processors are "limited unlocked" CPUs that can only have their multipliers increased by a maximum of 4. All Sandy Bridge processors have fully unlocked video cores, RAM multipliers, and power settings, so you can tweak your RAM and the iGPU with any motherboard.
You overclock a Sandy Bridge CPU by increasing the Turbo multiplier: that is, the one the CPU uses to automatically increase the clocks speed of its cores under load. If you raise the multiplier on a Core i7 980X Extreme chip, you're increasing its speed in all situations: idle and load. Raising the multiplier on a Sandy Bridge processor only raises the speed it will ramp up to under load; its idle speed remains the same. While this might seem limiting, in practice it works really well, since Turbo Boost is very, very good at deciding when to ramp up the clock speeds, and you benefit from dramatically reduced power consumption in low-load situations. Initially I didn't like this new overclocking mechanism but have come around after a few months' experience with it, and the older mechanisms now seem primitive. Since most of the overclocking mechanisms are built into the chip, the motherboard itself becomes less of a factor in overclocking than it was in the "raise the BCLK" days. Benchmark Reviews has published an in-depth article on Sandy Bridge overclocking.
MSI provides a number of overclocking mechanisms for the Z68A-GD80 motherboard. The one they're proudest of, however, is the "OC Genie" button: simply turn your system off, press this button so it latches down, and restart your system for an instant overclock. At system startup, MSI displays a warning screen telling you not to mess with BIOS settings while this button is down. On my Intel Core i7 2600K CPU, OC Genie set the turbo multiplier to 42, left the bus speed alone (good call) and increased the memory speed by selecting the first XMP profile, bumping it from 1333MHz to 1600MHz. MSI's scheme also overclocks the integrated GPU.
MSI refers to this as "instant overclocking", and indeed it is. ASUS' automatic overclocking mechanism tries increasing the bus speed and multiplier in tiny steps, running a stress test, then increasing them again. When the system crashes, it reboots with the last known good settings. I don't know if MSI simply uses a table with known safe overclocks for each currently available Sandy Bridge processor, but it achieves similar results much more quickly. Neither system will increase the stock processor voltage, though, which limits the overclocking potential. So, let's see what I can reach "by hand"...
And...the exact same results I've had with this processor on the ASUS Z68 motherboard. Increasing the bus speed or multiplier past these specs would result in crashes during benchmarking, so the 5GHz grail remains out of reach, even with the cooling provided by the massive Thermalright Silver Arrow cooler. Still, this overclock represents a 29% speed increase from the standard 3.8Ghz Turbo Boost frequency, and applies to all four cores under load rather than the single core the stock 3.8Ghz applies to. This performance differential was reflected in the benchmarks. This is the highest "on air cooling" frequency I've seen with an Intel quad-core processor. Note, however, that I needed 1.44V to reach this overclock. Intel specs the maximum voltage for the 2600K as 1.52V, and convention wisdom is that running anything over 1.4V for extended period of time is probably not in the best interests of the longevity of your CPU.
If you prefer to do your overclocking from directly from within Windows, you can use MSI's ControlCenter application:
You can also save and recall multiple overclocking profiles, which is handy.
One more thing: with older processors, you knew your overclock failed when your system crashed. Sandy Bridge CPUs, on the other hand, are very clever about automatically reducing their clock speed when the CPU core temperature gets too high. You might think that overclock is working perfectly, but behind the scenes your processor is clocking itself down when things get too hot. Keeping a utility like CPU-Z open during your stress tests will let you see the core speed "live" so you'll know if this happens.
Let's take a look at how the performance of the stock and overclocked configurations compares:
The MSI Z68A-GD80 benchmarked slightly slower overall than the ASUS P8Z68-V Pro. The main problem is the strangely low PassMark 2D, PassMark 3D, and SPECViewPerf Maya scores, where the iGPU is more of a factor. The OC Genie added an average of just over 25% better performance, while my manual overclock, although slower than the OC Genie overclock in a few tests that favored the iGPU, was about 34% faster overall.