June 23, 2022

AMD clarifies the power usage limits of its next-gen AM5 processors (and why it matters)

Enlarge / That “170W” number caused some confusion earlier this week because there are so many different numbers you need to know to understand CPU power consumption now.

AMD

AMD released some of the first details about its upcoming Ryzen 7000 processors, 600-series chipsets, and new AM5 CPU socket earlier this week. We learned that Ryzen 7000 chips will run at least 15% faster than comparable Ryzen 5000 processors and will require DDR5 RAM. We’ve learned that all Ryzen 7000 chips will ship with RDNA2-based integrated GPUs, though AMD still plans to offer a separate line of APUs with higher performance integrated graphics for people who want to play games. And we discovered some details about how PCIe 5.0 support works for SSDs and GPUs.

Another piece of information provided by AMD concerned socket AM5 power limits – the amount of power that an AM5 socket will be able to supply to a processor. Power limits have become more important to PC builders and enthusiasts as core counts have increased and power consumption has increased. Some of our recent Intel CPU reviews have explored how differently the same CPU can perform with different power settings, although we’ve also found that increasing performance in this way can have diminishing returns (that’s i.e. you can double your power consumption without doubling your performance).

AMD’s processors can work the same way, although the terminology is different. Intel uses different power limits, with the PL1 value determining power consumption under a sustained workload and the PL2 value determining how much power the processor can use in short bursts (a third number, Tau, defines how long during which the processor will operate at this PL2 limit). AMD has some acronyms for different figures of power, but the most relevant is Packet Power Tracking (PPT). PPT is the maximum power a CPU package can draw from the CPU socket.

Both Intel and AMD use thermal design power (TDP) numbers. These are related to heat generation and cooling, but they usually end up being a good indicator of sustained power consumption.

The AM4 socket has a PPT of 142W and supports processors with TDPs up to 105W. AMD’s original announcement and press briefings made it appear that the AM5 socket would support a PPT of 170W, a modest increase over AM4 but well below the 241W that Intel’s LGA1700 socket can provide. Thursday, AMD clarified at Tom’s Hardware that the 170W number refers to the maximum TDP of socket AM5 processors, and the PPT number could go up to 230W, which is much higher than AM4 and more in line with Intel’s platform.

Support for higher TDP and PPT values ​​will have the most noticeable effect on heavily threaded workloads that run for more than a few minutes, such as video encoding tasks and CPU-dependent rendering jobs . When we tweaked Intel’s power limits in other reviews, benchmarks like Cinebench and our Handbrake video encoding test show the most noticeable improvements, while more variable, single-threaded workloads like general use and gaming don’t benefit much. In short: expect the 12- and 16-core Ryzen 7000 processors to run faster and longer than their Ryzen 5000 counterparts, even if that means more power consumption and more heat.


Source link