Thermal Pads, Backplate Cooling, And Wrapping Up
Thermal Pads: A Miracle or an Illusion?
Next, we'll look at the tape that XFX uses to cover its VRMs. The tape isn't made from a homogeneous material, which would have surely been expensive to manufacture, but rather a foamed mass that is compressed in relevant parts thanks to pressure applied by the assembled card.
Unfortunately, air is one of the worst mediums for transporting heat due to its terrible thermal conductivity. Thus, if compact thermal pads of sufficient thickness and quality are available, we highly recommend using them instead of the stock foam.
Thermal pads (or tapes) are readily available for little money in a variety of thicknesses (and colors). The depression marks on the original tape provide some help on how and where to properly position the product of your choice.
- The best thermal pad is just good enough
- Avoid foamed pads if possible
- Never use thicker pads than necessary
- Nevertheless, make sure that there is sufficient pressure on the product
Using the Backplate as a Cooler
Nothing improves cooling like an increase in surface area! So now we're going to show you how to convert an existing backplate to a valuable part of the thermal solution.
Let us quickly flash back to the images of the backplate and the foil glued inside. This foil should either be removed completely (as shown in the picture below) or removed partially with something like an X-Acto knife. You'll want to thoroughly clean any spot that'll be in contact with the thermal pads. Remove any adhesive residue and fingerprint oil. The previously-mentioned 2-propanol comes in useful here.
Keep in mind that with very soft or thin backplates, slight pressure could be enough to make the plate touch the PCB. Thus, the nonconductive foil should only be cut and removed where necessary, or additional tape should be used as an insulating layer in relevant areas. Since this tape can also dissipate heat, that's the preferred solution.
In our specific example—the XFX RX 470 4GB—we put two-millimeter-thick thermal pads directly below the GPU package and one very hot memory module. We used a bit of thermal paste to further improve contact with the backplate, since the plate's inner surface isn't very smooth and also bends slightly under tension.
Since the backplate has a number of ventilation holes, we briefly put it back on prior to installation and marked the holes on the thermal tape. This makes it easier to apply the paste in such a way that there is none in those areas, keeping it from spilling out of the holes. This step is especially easy to see on the yellow pad over the VRMs, where the little blobs are positioned exactly between the holes.
How much can we expect to gain from all of this? We will start with a look at the GPU, which obviously profits from lower PCB temperatures.
These aren't awe-inspiring improvements, but every degree saved is a positive step forward. The memory modules benefit most, as they now remain well below 194°F (90°C). While this primarily helps operational reliability and durability, it also opens up overclocking opportunities that weren't there before.
If you're wondering why our graph is missing a bar, that's due to the fact that we had to completely disassemble the card to remove its backplate. Therefore, measurements in the card's original state were unfortunately not possible.
- Remove glued-on foils and remove glue residue
- Ensure a clean application of the thermal pads; optionally use thermal paste where necessary
- Be aware of holes in the backplate
- Avoid short-circuits (conduct a visual inspection, insert a sheet of paper for testing)
While it would be wrong to expect (expensive) thermal pastes to deliver miracles, they can serve up significant improvements. The optimized tightening of screws, the use of better thermal paste, and a more careful application of said paste (usually not possible during mass production) can all contribute to measurable gains.
If you want a bit of extra-curricular reading, we recommend expanding your knowledge of thermal pastes before making a purchase. Our recommendations are based on experiences gleaned from the lab. There may be better products out there we simply haven't used yet. Still, we consider our approach to be a good starting point.
Furthermore, it is a good idea to include your card's backplate in the overall cooling solution, as this step is almost always worth the effort. In addition, it would be wise to question existing fan curves, and appropriately adjust them to any temperature changes. Just remember that modifying the fan curve makes the most sense after tuning your card's backplate, since you could see augmented cooling on components back there, such as memory modules.
In the end, it can definitely be worthwhile to go the extra mile and not just replace your graphics card's thermal paste. If you are going to work on improved cooling, think beyond that one step and consider all of the factors that affect cooling, acoustics, and overclocking. You'll also have to consider whether spending about $20 on materials, plus the time and possible loss of warranty, are worth it. Often enough, the extra money could just as easily be invested in a better-equipped graphics card with the same chip, but better properties.
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