Using RivaTuner 2.11+ to edit Auto fan speeds

FOR ADT7473 ONLY

While this is nothing new and I don't pretend to have discovered this, I noticed that we don't yet have a guide to using the new RivaTuner functionality of editing the automatic fan speeds.

All modern cards, thankfully, have an automatic fan speed control that scales fan speed up and down with core load. High temps = high speed, low temps = low speed - the fan "duty cycle" is a linear function of the gpu temperature. However, sometimes the manufacturer doesn't get the balance quite right, and for whatever reason you want to edit the duty cycle yourself, either to reduce noise or improve cooling. While there are a number of ways to do this, the most popular being a BIOS edit and reflash, this RivaTuner method allows you to make these changes without risking future Catalyst/nVCP driver packages not recognising your custom BIOS and refusing to install, as well as reducing the risk of card bricking due to improper flash.

What you'll need:

• RivaTuner - current build 2.24
• Duty cycle spreadsheet (attached) - I take no credit for this excellent tool

Changing fan speed

• Install and launch RivaTuner. Navigate to the "Power User" tab, and scroll down until you find the "RivaTuner \ Fan" line entry. Expand it, and change the AutoFanSpeedControl string to "3". We've just told RivaTuner to let us not only view the fan speed controls but to allow us to edit them.
  
• Return to the Main tab and open up the Low-Level System Settings window for the adapter you want to edit. If you're not familiar with RivaTuner, this is done by first selecting the adapter you want to edit in the "Target Adapter" drop-down box, clicking on the small triangle-within-square button just beneath the field, and then clicking on the first of the icons that appear (mouse-over will bring up the description). Once the Low-level System Tweaks window appears, change to the Fan tab.
  
  From here, you could force a constant fan speed via the "Fixed" slider, but that would be boring and unnecessary. Instead, you'll see in the box the line entries for the "Auto fan speed control rule". These are what we're going to edit.
  
  A brief explanation of what everything does:
  
  • Duty cycle min: Minimum fan speed allowed.
  • Duty cycle max: Maximum fan speed allowed.
  • T min: Temperature lower boundary. When core temps drop to or beneath this, fan speed is at Duty cycle min.
  • T max (not shown or available to edit): Temperature upper boundary. When core temps rises to or above this, fan speed is at Duty cycle max. RivaTuner will not allow us to edit this value, instead, we need to edit the T range below.
  • T range:The result of a complicated formula which basically determines the nearest viable T max value compared to what we actually want it to be.
  • T operating, T low, T high: These all relate to dynamic control of T min. We don't want that, we want a linear relationship between fan speed and temperature according to the limits we set, so these need to be disabled by assigning values your card will never reach - so 151, 0, 151 respectively.
  
  
• While the sensor chip used on most cards that we're manipulating here and that this guide is written for (ADT7473) is fairly precise, it's usually not too accurate. Thus, we need to find out the difference between core temperature and the temperature registered by the sensor so we can adjust our settings to compensate - this is termed T offset.
  
  Fortunately, this is quite simple.
  
  Now that you've seen what we're editing, cancel out of the Fan tab, close the Low-Level window and return to the Main window, and open up the Hardware monitoring graph view in the same way as you opened the Low-Level System Settings window (make sure you're not putting load on your GPU for this next step). Take note of the GPU core temperature. Now, right-click on the GPU core graph and open up Setup. Under General settings, at top, change the data provider from Default to ADT7473.dll (there may be multiple ADT listings, they should provide the same data). OK out, return to the graph, and see if the GPU core temperature listed has changed by a significant margin. If it has, take note of the difference, and make sure to incorporate it into your calculations for the next step.
  
• Open up the Fan Duty Cycle Calculation spreadsheet. This nifty little thing will do the hard work for us. What you want to do here is simply decide what you want the new T min and T max to be (remembering the offset you worked out previously), and perhaps whether you want to make changes to Duty cycle max and Duty cycle min, and then plug those new values into the orange boxes at left. The spreadsheet will show you what these values will do to fan speed at various temperatures, as well as calculating the appropriate T range figure. However, there are only a few valid T range figures that will be accepted by the controller, so you need to look in the table at lower left and take the closest available instead.
  
  As an example, my new 4870X2 settings are T min of 50 with a T range of 40, giving me a T max of around 90. These settings ramp up the fan speed much more aggressively and mean that my card stays a lot cooler when gaming.
  
• Return to the Fan tab in Low-level. Check the the "Enable low-level fan control" box, click the "Auto" button, and enter into the field below the new T min, T range (while RivaTuner will not accept decimal places, it will automatically convert your entry to the nearest valid T range entry, so just round to the nearest integer), Duty cycle (if you've decided to change them), and T operating, low and high values (remember you want these last three to be 151, 0 and 151 respectively). Hit "Apply", and you should hear your VGA card fan adopt your new settings. Test them out to make sure you're comfortable with your changes, and then check the "apply on startup" box.

Enjoy! I don't pretend to be an expert, this is merely my distilled understanding of reading up on the subject, so if you're more in the know and I've got something blatantly wrong please correct me ;)

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