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One downside is that the TDP is almost doubled (170/~230 W vs 105/140 W for default/PPT) which may be a dealbreaker - certainly for my SFF system where I'm not
by joshvm 4y ago
One downside is that the TDP is almost doubled (170/~230 W vs 105/140 W for default/PPT) which may be a dealbreaker - certainly for my SFF system where I'm not sure I can cope with another 100W. These are limited by the socket really (AM4/AM5), but still it's nice to have that many threads in such a low power budget. I'm more curious to see what the 32-thread competition turns out to be in the same TDP bracket.
- db48x 4y agoTDP are made up numbers. Since they are arbitrary, you can't meaningfully say that they have doubled.
- wmf 4y agoIt's not that made up. 5950X used 120-140 W and I expect the 7950X to use 210-230 W. AMD said that the increased multicore performance comes from a higher power limit.
- db48x 4y agoI’ve no doubt that the newer cpu will use more power, but the numbers are made up. They’re picked by the marketing department using a formula, and calling them “watts” to try to make them look like energy used or heat dissipated doesn’t make them real. They don’t correspond to numbers that you can actually measure in any way.
- joshvm 4y agoWhether or not what marketing calls it is accurate, Anandtech measure power draw in their reviews and (at least in this example) it's pretty well aligned with the advertised TDP/PPT: https://www.anandtech.com/show/15043/the-amd-ryzen-9-3950x-review-16-cores-on-7nm-with-pcie-40/2 https://www.anandtech.com/show/15043/the-amd-ryzen-9-3950x-r...
- trashtester 4y agoThe 105W for the 3950X doesn't include package power. Add that, and it's closer to 150W (at least for me). This is before enabling PBO.
- db48x 4y agoThey measured one “105W” TDP chip maxing out at 86 Watts, and another “105W” TDP chip maxing out at 144 Watts? That’s not “pretty well aligned” with anything.
- chrismorgan 4y agoSee the part of the article starting at “We’ll first start with iso (like-for-like) comparisons between Ryzen generations, with iso-power.” That shows “up to +37%” at 105W.
- joshvm 4y agoThis is true, but there can be advantages to having 32 cores over 16, depending on your workload.
- chrismorgan 4y agoI’m not sure what you’re saying. Both the 5950X and the 7950X are 16 cores/32 threads.
- joshvm 4y agoSee my original post. I have an SFF case with a water-cooled 5950X+3090. That's already borderline for noise and thermals on a 240mm radiator, so an extra 100 W for the 7950X would probably be untenable. But as people point out - more perf per watt would probably mean cooler performance in a lot of workloads. It'll be interesting to see what the ITX options are for AM5 anyway.
- neogodless 4y agoTry to think of TDP as "thermal headroom." It's not efficiency or power consumption. It's room for the CPU to speed up when it's necessary. The boost max going from 4.9Ghz to 5.7Ghz (16%), and at the high end, the power necessary to increase clocks ramps up. In another slide, they indicated ~62% lower power at the same performance levels of the Ryzen 5000 CPUs. So more efficient, but also able to clock higher and get work done faster. For a thermally constrained system, you won't achieve the absolute maximum performance if the CPU throttles, but you do very much benefit from a more efficient architecture (+13% IPC) and process node.