Computer

Truths and lies about the Intel Core 12: AVX-512 and its consumption

When Intel announced its Alder Lake architecture for laptops and desktops, a relevant omission could be seen, the lack of support for the AVX-512 instructions in the Golden Cove cores, these renamed as P-Cores. Of course, when Intel started talking about Sapphire Rapids and the use of Golden Cove, those instructions came out again. Were we in front of two different nuclei under the same name? The reality is that time has shown that it is possible to activate these instructions by turning off the E-Cores and activating their use from the BIOS.

AVX-512 instructions are of the SIMD type, which means that they are parallel instructions where only one of them is executed simultaneously with several simultaneous data, in this case up to 512 bits of data. Which means that the processing capacity per clock cycle is much higher when executing them, but since the data movement is much larger, the consumption is affected in the process.

Efficiency of the Intel Core 12 with AVX-512

AVX-512 Core 12 Efficiency

The folks at Igor’s Lab have run a series of performance and efficiency tests on an i9-12900K with both the AVX-512 instructions being active and not. The motivation for which they have done this is because the information given by HWinfo gives a much lower consumption using the AVX-512 instructions, which is unnatural, since these types of instructions increase consumption by their nature. So they have decided to measure it themselves and the numbers speak for themselves.

To begin with, if we take into account the consumption of the i9-12900K using its standard configuration of 8 P-Cores and 8 E-Cores, we find that they have measured a consumption of 208W compared to the 255W that HWInfo gives. Deactivating the efficient cores and stressing the P-Cores to the maximum again the results are again lower with 274W compared to the 328W of the previous information. The surprise? Power consumption with the AVX-512 drops to 253W. What happens when in theory they should be higher?

AVX-512 Core 12 Efficiency

One of the tests they have done has been with Far Cry 6, playing the Ubisoft game in Full HD, with ultra quality, but without the high definition texture package to see if the phenomenon repeats itself:

AVX-512 Core 12 Efficiency

And indeed, again we can see how HWinfo gives consumption figures much higher than normal, and that while having the AVX-512 should increase the watts consumed, activating it places it practically at the consumption of the CPU in its operation. habitual. This would lead us to think that the CPU clock speed has been cut internally, however, the difference in gaming is a single frame per second, therefore this fact is ruled out, the clock speed is the same.

Conclusions

Contrary to what happened with previous generations of Intel CPUs, the AVX-512 instructions in the Core 12 are more efficient and do not cut the MHz, this is an important step forward for Intel after years in which they had been put in the fabric of judgment for poor energy efficiency.

The use of these instructions is not given at the domestic level to the same level as other markets, the reason for this is that they have not been adopted by AMD so far, although we will not see them until Zen 4. In any case, this shows that These have a future, since everything indicated that they would be replaced over time by the new AMX, as well as various acceleration units.

As a final note, it seems that for consumption the P-Cores alone when the AVX-512 is not active has a bug that we hope Intel will solve.

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