The next major leap in CPU design will not come from increasing the number of cores, pursuing smaller process nodes, or stacking more chips onto a single CPU. This is not to deny that technologies like AMD's 3D V-Cache are excellent and significant innovations, but they haven't truly changed our inherent understanding of CPUs.
Rear power supply technology
Rear-side power delivery is one of the CPU innovations I've been truly looking forward to. This revolution will not only reshape the enterprise market but also revolutionize performance, cooling, and energy efficiency, especially for PC builder and enthusiasts.
The power source for a CPU is crucial.
Simply put, rear-side power delivery refers to moving the power supply network (PDN) from the front to the back of the silicon chip. This PDN, essentially composed of metal layers and vias, is used to supply power to transistors. Traditionally, it resides on the same side as data I/O, forcing engineers to make trade-offs between performance and efficiency. Power routing competes with logic signals, and any congestion can lead to resistance and voltage drops, ultimately limiting chip density.
By moving power delivery to the other side of the chip, the importance of these trade-offs is greatly reduced. The front can be entirely dedicated to signal output and transistors, while the back can provide power. Companies like IMEC and TSMC have been experimenting with this on lab chips for some time, but Intel's PowerVia PDN is the first rear-side power delivery implementation for a commercial chip. While initially planned to launch alongside Intel's 20A process node, it wasn't released due to this node not being geared towards consumer platforms. However, this doesn't mean we won't see PowerVia in the near future. The Panther Lake architecture, based on Intel's 18A process node and featuring PowerVia technology, is expected to launch in laptops in January 2026. The upcoming Arrow Lake desktop processor upgrades will not utilize Back-of-Side Power Delivery (BSPD) technology, but the Nova Lake desktop CPUs, launching at the end of 2026, may adopt it. However, it's currently unclear whether these chips will be manufactured using Intel's 18A process node.
Power delivery
Power delivery is one of the behind-the-scenes bottlenecks that most PC enthusiasts never consider, yet it quietly determines the performance limits of a CPU. Every watt of power consumed by the processor must be delivered downwards, which can interfere with logic signals, increase resistance, and add latency. This is why some high-end chips encounter voltage stability limits before reaching their thermal limits.
PowerVia technology
Technologies like PowerVia can reduce so-called IR drop, the voltage loss that occurs during power transmission. Higher efficiency means transistors can operate more stably at their design voltages, resulting in a more stable clock frequency. Intel's own tests show that, at the same process node and voltage, moving the power supply circuitry to the bottom of the chip increased the clock frequency by 6% and reduced the voltage drop by 30%.
The thermal advantages are also obvious: moving the power supply circuitry to the back allows for better contact between the logic circuitry and the integrated heatsink (IHS), and the CPU cooler can also make direct contact. Theoretically, this helps simplify CPU cooling and reduces the impact of voltage spikes during load operation.
Back-mounted power supply also aligns perfectly with future stacking technologies. Current 3D vertical cache and chipset architectures rely on through-silicon vias (TSVs) and dedicated bonding layers. Freeing the top of the CPU from its power network allows for true logic stacking, not just additional cache. This could manifest as the CPU core layer being directly bonded to an AI accelerator or integrated GPU without a separate substrate.
As process nodes shrink, the cost of producing usable wafers rises dramatically, ultimately being passed on to consumers. Furthermore, silicon manufacturing capabilities are nearing their limits: gate lengths are measured in units of tens of atoms.
In other words, the massive advancements we saw in the 2000s and 2010s are no longer present in the 2020s. The future will primarily rely on technologies like back-side power supply to improve density and efficiency, as well as new transistor designs such as GAAFET and RibbonFET.
A cleaner power supply means more stable overclocking and bucking, fewer transient spikes causing crashes or throttling, and more consistent thermal performance. Additionally, mobile power supplies can deliver approximately a 6% performance improvement.
While it may not be as immediately apparent as core count, entirely new architectures, or AI accelerators, back-side power supply design is a truly significant advancement in modern chip design. It rethinks the physical limits of power delivery within the CPU, and this transformation promises to spur further innovation.
Source: Content compiled from XDA
