The Dual Boot Mac Blog

Everything you need to know to get started and a little bit more….


AMD 6750m (original guide by macrumors member necriss HERE):

This guide is specifically for the AMD 6750m however the tools used will work with any of the AMD/ATi mobile GPUs that Apple use in the iMac and Macbook Pro line.

The tools you will need are:

Before we begin I would just like to clearly state that by over clocking your GPU, you are doing so with your own free will and know that the results are never guaranteed and could result in harming your computer.

Now, by default the 6750m runs 600/800 (core/mem) at 1.00V, however these clocks run fine at 0.855V. This means that it is possible to over clock using a voltage lower than stick, thus enabling faster performance at lower operating temperatures. For example, you can clock the core/mem at 750/950 at 0.955V.

You can always choose to overvolt(clocking at a voltage greater than 1.0V) for a higher overclock, but you would do this at your own risk, always use GPU-Z to keep an eye on your GPU temperature.

Once you have installed ATT follow the simple instructions in the image below to set up your overclock:

Right click on ATT in the system tray and select over clocking.

Ticking “include clocks in profile” allows you to save the current clocks as a profile for easy access of for automated over clocking in “Game Profiles”.

If you wish to clock your GPU at higher than stock voltage, make sure that your laptop(if you are using one) is plugged in to a power supply and windows power options are set to “Performance”.

ATT lets you set up game profiles so that a set over clock you have saved will run whenever you start to play a selected game.

Crysis 2 Benchmarks:


Nvidia GT650m:

This is the most up to date GPU that Apple are using, currently only in the macbook pro line, other chips from the same “kepler” family will be coming in the next batch of iMacs to be released.

Once again the tools mentioned here should work for any of the Nvidia chips but please realise that each chip is different so make sure you monitor your GPU constantly with GPU-Z when doing any over clocking. Make sure you have downloaded and installed the latest driver available from Nvidia.

Most of the information here was found on the forums and was posted by a user called “mobious 1”. If you are looking for more in depth discussion then I suggest you head over HERE now.

First of all you will need GPU-Z as mentioned previously and also Nvidia Inspector which can be found HERE.

The first thing we have to do is to alter the power state of the GPU, you will need to either use the CMD window or create a batch file in the Nvidia Inspector directory. To do this for the GT650m you will need to change the Pstate to P2. Create a notepad file in the directory for Nvidia Inspector and write this in it: nvidiaInspector.exe -forcepstate:0,1 then rename the file pstate2.bat

The power states:

P8 = idle clock speeds and lowest power consumption
P2 = the default mode used when your PC boots or no drivers are installed.
P0 = Gaming/Load. This mode only accepts boost/offset values

Once the file has the .bat extension all you need to do is double click it to run, this saves repeatedly typing things in a command window.

Other commands that you will need to create/edit:

nvidiaInspector.exe -setBaseClockOffset:0,0,135 -setMemoryClockOffset:0,0,500 -setpowertarget:0,111 -setVoltageOffset:0,0,187500 -setGpuClock:0,2,1311 -setMemoryClock:0,2,3500 -forcepstate:0,2

nvidiaInspector.exe -forcepstate:0,8

nvidiaInspector.exe -setVoltageOffset:0,0,0 -setGpuClock:0,2,705 -setMemoryClock:0,2,3000 -forcepstate:0,16

Mobile keplers do not have a voltage offset, keep -setVoltageOffset:0,0,0 and do not modify it.

The commands above are self explanatory. Simply adjust the offsets/values to suit. I use shortcuts to execute these batch files, making idle<->overclock an easy toggle.

This is the basic starting point for over clocking your Nvidia GPU, results may vary wildly depending on your exact machine so please only increase speeds gradually and always monitor the temperatures using GPU-Z.


Others and Older GPUs:

For very basic over clocking it is possible to just use the MSI Afterburner app, performance of this again varies from computer to computer and generally it will only result in small performance boost.

Here are some guides for older GPUs:

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