Since there’s a never-ending debate about backplates helping or not helping thermal performance, we decided to test with and without one in place. As mentioned, Sapphire puts pads between the back of its PCB and the backplate right behind the voltage regulation circuitry. It also indents the plate above that area.
We’ll soon see that this can help cool the voltage converters and the components around them. The GPU doesn’t really see a direct benefit, but overall, temperatures are observed to rise more slowly since less heat is transferred to the board itself through the VRM.
Let’s take another look at the back of AMD's Radeon R9 380X and its backplate to give the infrared images some context. The pictures illustrate what we just mentioned: the VRM is connected to the backplate via thermal pads, but the GPU does not enjoy any real advantage. This could have been done more efficiently by cutting a hole for the thermal pads into the isolation foil, which spans the entire surface of the backplate.
First we'll look at the Radeon R9 380X’s temperatures without its backplate at idle. The GPU operates at approximately 43 degrees Celsius, since the card employs a semi-passive mode with its fans disabled. The VRM's temperature is fine as well.
During our gaming loop, the GPU's diode measures less than the interface temperature due to its proximity to the heat sink; the PCB is actually warming the processor. Adding thermal pads here would have been the logical choice. Since the card forces fan speed higher until its temperature target is reached, any improvement would have resulted in a markedly cooler and quieter graphics card.
With the backplate in place, the temperature difference between the hottest and coldest part of AMD's PCA is 12 degrees Celsius. Without it, we measured the VRM's temperature at 93 degrees Celsius, whereas it’s now at 90 degrees Celsius in the same place, measured via a temperature probe inserted under the backplate. This slightly lower reading has a positive influence on the overall thermal story in the sense that the cover provided by the backplate doesn’t drive up the GPU's temperature. It usually does because the backplate makes it harder to dissipate the GPU’s waste heat.
Full Load Temperatures
Now we see what happens when the VRM delivers more than 250W to the GPU, much of which is dissipated as waste heat. Without the backplate, we’re looking at temperatures in excess of 113 degrees Celsius. That's well beyond acceptable. Consequently, thermal energy spreads across the PCB and heats the GPU from the back. Almost 84 degrees Celsius where Tonga interfaces with the PCB is massive. At that point, the card is both hot and loud.
With the backplate attached, the VRM's temperature is significantly lower at 107 degrees Celsius. The difference between the hottest and coolest parts of the board is now 18 degrees. This proves that a backplate can do more than look pretty and keep the graphics card stable. I can also make a positive impact on thermals if only a few square inches of padding are thrown in.
The VRM’s backplate-based cooling solution has ramifications for the fans as well. This makes sense, since the graphics card will try to achieve its target GPU temperature. Do higher temperatures from the back mean higher rotational speeds?
A comparison between the results with and without the backplate shows that Sapphire does a great job with its cooling solution.
|Ambient Temperature22 °C||Open Bench Table, Gaming Loop||Open Bench Table, Torture||Closed Case,Gaming Loop||Closed Case,Torture||VRM Maximum(Torture)|
|Sapphire R9 380X Nitro(With Backplate)||69 °C||74 °C||72-73 °C||79 °C||105 °C|
|Sapphire R9 380X Nitro(Without Backplate)||69 °C||73 °C||73-74 °C||80-81 °C||113 °C|