Intel’s Rocket Lake is expected to deliver a 20 percent improvement on the IPC, but new rumors suggest that the top-end version of the chip will still deliver a lot of power during a peak load. It is understood that the CPU runs up to 98C with a sustained power consumption of ~ 250W.
According to Chiphell reports, the Core i9-11900KF was tested with an entry-level 360 mm cooler during the AIDA64 FID stress test. One of the reasons you should use these rumors with a grain of salt is that the AIDA64 FID stress test is specifically designed to hammer the chip. This is great if your goal is to use voltage test equipment and isolate faults. It is less good if you aim to measure the power consumption of the normal workload. AIDA64’s FPU test also contains AVX-512 instructions. Using the code path for the Core i9-11900KF while clocking the CPU at 4.8 GHz will generate a lot of heat.
Image by Chiphell
Running the CPU as hot as 98C is less than ideal from an enthusiast’s perspective, but it may also show that Intel is comfortable running its silicone at this temperature. Years ago I had a conversation with an Intel engineer, who told me that the company expected the then Nehalem and Westmere processors to work perfectly at 24 ° C in 24/7 operation, and that the chips this temperature could handle for up to a decade, at least. That doesn’t mean enthusiasts should take out their expensive coolers and bake their chips under a $ 15 cooling plate + fan, but the fact that the CPU can work up to 98C is not automatically a problem.
It is not surprising (assuming this rumor is even accurate) to see the 11900KF run so hot. As we recently discussed, motherboard OEMs program enthusiastic boards with default settings that run the CPU on a full clock for a longer period than specified by Intel. Intel is aware of this and its own guidelines are recommendations, not requirements. Normally we would expect a CPU using AVX-512 code to make the switch itself. The fact that this did not happen could mean that Rocket Lake keeps its watches in AVX-512 workload, where other Intel processors are off. It can also indicate that the motherboard is set not to drop the multiplier during the AVX-512 while executing the AVX-512 code. The fact that this chip hit 98C in an unknown configuration does not mean that it will be normal behavior for every CPU.
Intel has chosen to push Rocket Lake as far as possible, while remaining backward compatible with Comet Lake, which includes defined TDP ranges. In this way, it does not differ much from AMD’s decision to keep the Ryzen 5000 series’ maximum TDPs identical to their Ryzen 3000 counterparts. Intel can still claim an increase in power efficiency, as long as it completes workload in less time than the 10th generation chips within the same power envelope.
Rocket Lake is expected to deliver strong performance improvements in single-threaded workloads and a slightly smaller increase in multi-threaded workloads. Comet Lake scored ten key points, while Rocket Lake offered only eight, but the IPC gains are expected to compensate mostly or completely. AVX-512 support may even give the eight-core Core i9-11900K some wins over the 10-core Comet Lake, though it depends on the benchmark support.
We’ll know more when Rocket Lake starts at the end of March.
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