THE CRUNCH
Conventional PC building wisdom says the graphics card goes in the top PCIe slot, but a modder known as TrashBench has been testing whether that placement is actually optimal. In a recent experiment with an RTX 3080 system, moving the GPU away from its usual position delivered up to a 19°C reduction in hotspot temperature, the reading taken at the hottest point on the graphics chip. The catch: that configuration made CPU temperatures worse.
The testing started from a conventional build, with the CPU cooled by a 360mm all-in-one liquid cooler and the triple-fan RTX 3080 in the standard PCIe expansion slot. TrashBench then ran a constant thermal load by looping 3DMark Time Spy and 7-Zip's built-in benchmark, with fan speeds locked for consistency, before trying the GPU at the bottom of the case, vertically, and on either side of the case's side intake fans. After balancing the best ideas for both chips, the final layout mounted the CPU vertically against the side intake fans, delivering a 3.3°C cooler CPU alongside a 14°C lower GPU hotspot.
Anyone tempted to experiment should note that a PCIe riser cable, an extension lead that lets the card sit away from the motherboard slot, is essential for repositioning a GPU like this.