Engineering Stories: Optimization of the Cooling Concept for the Sony PlayStation 5
This story is about the engineering that went into optimization of the Sony PlayStation 5 cooling system.
The original Sony PlayStation 5 was launched on November 12, 2020. The system is driven by a custom designed 8 core Zen 2 AMD CPU running at a frequency up to 3.5 GHz. The GPU is also a custom designed unit based on AMD's RDNA2 graphics architecture. The total power consumption is 350 W. To dissipate the heat away from the SoC, the original unit used a relatively heavy heatsink. The target of this project was to optimize the cooling system. As a result, it was possible to reduce the weight of the the heatsink by 300 g. In addition, noise emission was reduced by 2.5 dBA. Both aspects are generating direct benefits for the end user.
Assessment of the original design
The original heatsink consists of a large block of aluminium heatsinks with six embedded copper heatpipes. Two of them extend to the upper left aluminium heatsink. The circular cut-out is for the radial fan (see image below).
Let's look at the shortcomings of the original fan design: The ventilation is driven by a radial fan (diameter 120 mm, thickness 45 mm). The blades are not curved and they do not touch the hub at the center. This makes it easier to manufacture. However, for improved aerodynamic efficiency, the blades should be curved - thereby preventing premature flow separation.
Optimization of the cooling concept
To improve the convective airflow we can optimize both the fan and the heatsink. We will outline both strategies below.
1. Optimization of the fan
The original fan uses non-curved blades. They drastically limit the performance due to premature flow separation. In order to improve the aerodynamic efficiency, we start by defining the blade loading. Using an inverse design approach we can algorithmically guide the design of the fan blades. The difference between the original and the optimized fan is illustrated in the image below. Note the flat blades of the original fan (image below, left). Also note the curvature of the blades of the optimized fan (image below, right).
2. Optimization of the heatsink
The original heatsink uses cooling fins in areas with low air flow. Clearly, they can be eliminated without loss of cooling efficiency. However, due to the complex interaction of heat conduction and convection, it might be difficult for humans to identify redundant cooling fins. Therefore, the new shape of the heatsink was identified via adjoint optimization. As a result it combines two of the heatsinks into one longer heatsink whose fins are connected via a heatpipe (see image below).
Conclusion
Using modern fluid dynamics it was possible to reduce the weight and manufacturing cost of the heatsink by 40% (around 10% of the entire PlayStation 5 unit). Due to the increased efficiency of the new fan, the aeroacoustic performance is improved by 2.5 dBA. This greatly helps to enhance consumer comfort and to reduce the cost of this product.