Overclocking: Nvidia And D.O.T.
Once more, we’d like to offer a word of warning. Overclocking may damage your card, and if you make any changes, you do so at your own risk. Doing so may also void your warranty.
MSI’s Nvidia-based cards use the same D.O.T. (Dynamic Overclocking Technology) feature as the ATI models. Again, you can’t download it separately and are forced to use MSI’s modified driver instead if you want to take advantage of it.
While it’s a good deal fresher than MSI’s Catalyst-based driver, GeForce 182.06 is not as current as we would like. Nvidia’s official release is 186.16 at the time of writing (Ed.: a recent update to 190.38 increments Nvidia's GeForce suite yet again). The additional D.O.T. section is launched as a separate application in Windows. Just like its ATI counterpart, it comes with six predefined performance profiles. However, as it turns out, we could get far fewer of them to run stably.
Don’t let that fool you, though. Remember that MSI’s Lightning version of the GTX 260 (216 SPs) is factory-overclocked to begin with. While Nvidia’s stock setting for this card would call for a clock speed combination of 578/1,242 MHz (GPU/shader), MSI’s default setting already runs the card at 655/1,404 MHz. That the GPU and the shaders run at different speeds is typical of Nvidia’s designs.
|O/C Mode||Clock Speed (GPU/Shaders/Memory)|
|MSI D.O.T. Private||668/1432/1018|
|MSI D.O.T. Sergeant||681/1460/1038|
|MSI D.O.T. Captain||694/1488/1058|
|MSI D.O.T. Colonel||707/1516/107|
|MSI D.O.T General||713/1530/1088|
|MSI D.O.T. Commander||720/1544/1098|
Again, you’ll most likely have to find out for yourself whether a setting will work with your card. Our sample was stable up to the “Captain” D.O.T. level, but wouldn’t go any higher. Installing Nvidia’s latest reference driver deactivates the D.O.T. feature, causing its control panel to vanish as well.
As long as the setting you have chosen works, you won’t actually notice a difference (aside from the performance, obviously). If your card features an optimized fan speed profile, the fan will spin up to deal with the extra heat generated by the higher clock speeds. We recommend a little tool called GPU-Z if you want to keep an eye on your GPU’s temperature. It can also monitor fan speeds, clock speeds, and some of your graphics card’s various other vital signs. Additionally, GPU-Z can also create a log file, which is very handy if you want to check back on your card’s performance later.
Since you’ll only know you’ve found the ideal setting after the fact (namely, when you go over the log files or push your board one level too far), it’s best to keep your initial tests short. Normally, a GPU will reach its maximum temperature under load after two to five minutes. You should also take some readings at stock settings, allowing you to check on what’s changed, and to what extent. If the fan does not spin up, you need to keep a very close eye on the temperature.
To reduce the risk of damaging your card, you should start off with the smallest overclocking increment and apply the change. Since our Nvidia card is already overclocked by default, we have to be a little more cautious, since we’ll definitely reach its limits much faster. Once you’ve selected the profile you want to try, run a 3D benchmark to stress the GPU with the new settings.
You’ll know when you’ve exceeded your card’s limit if you see any of the following symptoms: rendering errors, inverted colors, a flickering screen, pixelation, solid blocks of color, or a frozen system. At that point, your graphics driver may restart, dumping you back to the desktop. Alternatively, your system may crash completely and restart, in which case you can forget about the increased clock speed.