AMD Socket AM5 Renders For Zen 4 Highlight A Potential Cooling Advantage Over Alder Lake
Back at CES 2022, AMD gave an update on the Zen 4 architecture that will first show up with the Ryzen 7000 series processors. Those chips, at least in desktop form, will go into Socket AM5. Where Socket AM4 (and most of AMD's previous mainstream processors) used a Pin Grid Array design, the next-generation Socket AM5 will adopt a Landing Grid Array design similar to the one used on Intel's processors since the venerable LGA 775, first used for later models of the Pentium 4.
You might be reading this thinking, "is that really necessary?" Well, yeah, actually. See, this information comes to us by way of Igor's Lab, who broke the story along with sharing a couple of CAD diagrams of the AM5 socket and its retention mechanism. Igor doesn't explain where he came across the information, but remarks that he decided to share it as a follow-up to his other recent story about the Intel LGA 1700 socket slightly bending installed processors, reducing cooling performance.
Thanks to some help from Buildzoid (of the YouTube channel Actually Hardcore Overclocking), it was determined that Intel's "Independent Loading Mechanism" (ILM) was at fault. The ILM is that clamp that locks down over the CPU to hold it in place while you install your heatsink. Because the ILM is secured to the motherboard, and because it places its load entirely in the center of the CPU horizontally, it's able to slightly bend the CPU package—not enough to damage it, or prevent it from working, but just enough to create a gap in the top that worsens cooling performance.
Washers between motherboard and ILM reduce bending and improve temps. Image: Igor's Lab
Igor proved his hypothesis by testing an Alder Lake system exhaustively using washers between the LGA 1700 socket's ILM and the motherboard. Testing with gaps of 0.5mm, 0.8mm, 1.0mm, and 1.3mm, he found that the greatest benefit was realized with 1.0mm-thick washers installed, effectively raising the ILM by 1 millimeter off the mainboard. That gave the Core i9-12900K CPU underneath his Corsair XC7 waterblock a full 5.76° drop in load temperature compared to the stock configuration.
That's a pretty handy tweak for Alder Lake owners, but didn't we start this post talking about AMD CPUs? As we mentioned earlier, according to Igor's information, AMD's Socket AM5 will actually attach its LGA socket's Socket Actuation Mechanism ("SAM," the AMD equivalent of the "ILM") straight through the motherboard to the heatsink backplate. Spreading the tensile stress across eight screws, including the four for the heatsink itself, should help guard against the deformation of the CPU seen in Alder Lake, but it also may improve the stability of heavy coolers attached to the backplate.
