Bulldozer is the dream CPU for overclockers. We show you how to push your chip that little bit further.
Bulldozer has finally landed, but it wasn’t quite the Intel killer many were expecting. While it’s a dab hand at multi-threaded applications, the sad fact is that most of today’s software still requires excellent single-thread performance. However, there’s one thing that Bulldozer does well that can help lift its performance dramatically – overclock. We’re going to show you how to do this, making the most of your Bulldozer FX-8150 CPU via a few simple tweaks in the BIOS. As with any overclocking guide, there’s a small risk you could damage your CPU and we take no responsibility for damage incurred from following our article. Having said that, we’ve gone for very conservative settings so the risk is minimal; the author has never damaged a CPU from overclocking in 15 years.
1. Ensure you’ve got the right gear
Even the most affordable motherboards now support overclocking, but it’s wise to check that your motherboard can handle Bulldozer overclocking before purchase. This means you’ll need access to the CPU’s multiplier, various voltage controls and the ability to disable power-saving features. Best of all is a motherboard that allows these settings to be configured within Windows so you don’t need to get your hands dirty in the BIOS.
You’re also going to need a decent cooler to remove the extra heat generated when operating at higher frequencies and voltages. Bulldozer is a rather hot chip even in the best circumstances, so we recommend going for the current king of the air-cooled market, the massive Noctua NH-D14. Make sure you can squeeze it into your case, as it’s not exactly small.
2. Disable all the junk
Depending on your motherboard, you can either access the following settings from within the BIOS or from overclocking software in Windows. The first thing you need to do is disable any options that can interfere with your overclock. If your motherboard has any automatic overclocking options, usually found in their own overclocking area, disable them entirely. Like Intel’s chips, Bulldozer automatically ramps up the frequency under load, and this option is usually called AMD Turbo Core in the BIOS – find this in the CPU features area of your BIOS and set to disabled. Finally we’re going to switch off Spread Spectrum, which should always be disabled, regardless of the type of chip being overclocked. Once this is done, reboot your PC and head back into the BIOS.
3. Feel the power
Before increasing the frequency, we need to supply the additional voltage necessary to run at the higher speed. Head to the CPU section of your BIOS and look for CPU Vcore. The absolute maximum voltage we recommend on air cooling is 1.4V -- anything higher than this requires water cooling or better. Be warned -- if you crank up the voltage above this point you risk damaging the CPU permanently. It’s better to be safe than sorry and stick to 1.4V as the maximum voltage. Reboot the PC and head back into the BIOS.
4. Adjusting the multiplier
There are several ways to overclock Bulldozer, but we’re sticking to the simplest method: increasing the multiplier. Like the Intel K-Series, this is stupidly easy and can give you a significant performance boost. The frequency of your Bulldozer CPU is determined by multiplying the CPU Host Clock (also known as the HTT) by the multiplier. The default speed of the host clock for Bulldozer systems is 200MHz, but if you want to get even better performance you can overclock this as well. However, it’s a much more complicated process, so we’re going to leave the Host Clock at default speed.
We’re aiming for a first overclock of 4.4GHz, which is a moderate speed increase over the FX-8150’s default turbo speed of 4.2GHz. To do so, head to the CPU Clock Ratio in your BIOS (this is the multiplier), which will be found in the CPU or tweaking section. Because we’re sticking with the 200MHz Host Clock, we’ll need a multiplier of 22 to hit this frequency. Increase your CPU Clock Ratio to 22 and reboot into Windows.
5. Stable as a rock
If you’ve made it into Windows, congratulations! Your chip is running 10% faster than the default speed, so now it’s time to test for stability. A very simple application that does a decent job of heating up the CPU is SiSoftware Sandra, which can be downloaded for free
here. This application has a burn-in option, so set it up to run the burn-in on just the CPU (disable all the other burn-in options). Leave Sandra running for a couple of hours, while also paying close attention to your CPU’s temperature (your motherboard should include temperature-monitoring software). If it goes over 60°C you need to either get better cooling or drop the CPU voltage, as 61°C is the maximum operating temperature recommended by AMD. Once you’ve managed to keep the PC running for a couple of hours, it’s time to reboot and head back into the BIOS.
6. Crank it up
Once again we’re going to adjust the CPU Host Ratio (or multiplier), which in turn will increase the CPU frequency. Jack it up a single point, which will increase the CPU’s frequency by 200MHz up to 4.6GHz. Reboot the PC and head back into Windows. Do step 5 again to ensure the new frequency is stable, and then it’s a case of rinse and repeat. Keep testing for stability, then increasing the multiplier by a single point until the PC becomes unstable. At this point, decrease the multiplier back down to the last safe value and enjoy your faster CPU. The FX-8150 is regularly hitting 4.6GHz or better on air, with 5GHz possible if you’re lucky.
