Intel Core i7-10700 vs Core i7-10700K Review: Is 65W Comet Lake an Option?
by Dr. Ian Cutress on January 21, 2021 10:30 AM EST- Posted in
- CPUs
- Intel
- Core i7
- Z490
- 10th Gen Core
- Comet Lake
- i7-10700K
- i7-10700
Conclusion: TDP is Not Fit For Purpose
In years gone by, processors were sold with a single frequency and power rating. It was very quickly realized that if a processor could effectively go to sleep, using either lower voltage or lower frequency (or both) then a lot of idle power could be saved. Going the other way, processor designers realized that for temporary short bursts, a core could run at a higher frequency before it reached a thermal limit. Also, using a multi-core processor meant that either the power budget could be shared across all the cores, or it could be focused in one.
Both AMD and Intel have noticed this over time, and both companies have different attitudes on how they report numbers relating to ‘base frequency’ and related power as well as the bursty ‘turbo frequency’ and related power. Out of those four metrics, the only one Intel doesn’t provide is turbo power, because from their perspective it is system dependent.
Intel lets motherboard manufacturers determine how long a system can turbo for, and what that budget is. Intel encourages motherboard manufacturers to over-engineer the motherboards, not only for overclocking, but for non-overclockable CPUs to get the best performance for longer. This really messes up what the ‘default out-of-the-box performance’ should be if different motherboards give different values. The trend lately is that enthusiast motherboards enable an unlimited turbo budget, and the user building their system just has to deal with it.
This means that users who buy the Core i7-10700 in this review, despite the 65 W rating on the box, will have to cater for a system that will not only peak around 215 W, but sustain that 215 W during any extended high-performance load, such as rendering or compute. We really wished Intel put this 215 W value on the box to help end-users determine their cooling, as without sufficient guidance, users could be hitting thermal limits without even knowing why. At this point, 'Intel Recommended Values' for turbo time and budget mean nothing outside of Intel's own OEM partners building commercial systems.
Core i7-10700 vs Core i7-10700K Performance
In the review we highlighted that these two processors have a peak turbo frequency difference of 300 MHz and an all-core turbo frequency difference of 100 MHz. The fact that one is rated at 65 W and the other is rated at 125 W is inconsequential here, given that most end-user motherboards will simply enable turbo all the time. This means the performance in most of our tests between the two is practically identical, and consummate to a 100-300 MHz frequency difference.
In practically all of our tests, the Core i7-10700K is ahead by a super slim margin. At $387 for the 10700K compared to $335 for the 10700, the performance difference is not enough to warrant the $52 price difference between the two. Performance per dollar sides mostly with the Core i7-10700, although users getting the i7-10700K will likely look towards overclocking their processor to get the most out of it – that ultimately is what to pay for.
The other comparison point is with the Ryzen 5 5600X, which has two fewer cores but costs $299. In practically every test, the increased IPC of the Ryzen over Intel means that it sits identical with the Core i7 processors, AMD is cheaper on list price, and at a much lower power (AMD will peak around 76 W, compared to 215 W). AM4 motherboards are also abundant, while corresponding Intel motherboards are still expensive. The problem here however is that AMD is having such high demand for its product lines right now that finding one in stock might be difficult, and it probably won’t be at its recommended price.
Users in this price bracket have a tough choice – the more efficient AMD processor that might be in stock, compared to the Intel processor that will be in stock but more cooling will likely be required.
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dullard - Thursday, January 21, 2021 - link
Yes, it is sad that even well respected PhDs in the field can't seem to understand that TDP is not total consumed power. Never has been, never will be. TDP is simply the minimum power to design your cooling system around.I actually think that Intel went in the right direction with Tiger Lake. It will do everyone a service to drop any mention of TDP solely into the fine print of tech documents because so many people misunderstand it.
Yes, TSMC has a fantastic node right now with lower power that AMD is making good use of. Yes, that makes Intel look bad. Lets clearly state that fact and move on.
Power usage matters for mobile (battery life), servers (cooling requirements and energy costs), and the mining fad (profits). Power usage does not matter to most desktop users.
dullard - Thursday, January 21, 2021 - link
Also don't forget that we are talking about 12 seconds or 28 seconds of more power, then it drops back down unless the motherboard manufacturer overrides it. The costs to desktop users for those few seconds is fractions of a penny.bji - Thursday, January 21, 2021 - link
"minimum power to design your cooling system around" makes NO SENSE.You don't design any cooling system to handle the "minimum", you design it to handle the "maximum".
It sounds like you've bought into Intel's convoluted logic for justifying their meaningless TDP ratings?
iphonebestgamephone - Thursday, January 21, 2021 - link
Why are there low end and high end coolers then? Arent the cheap ones for the minimum, in this case 65w?Spunjji - Friday, January 22, 2021 - link
dullard's comments are, indeed, a post-hoc justification in search of an audience.dullard - Friday, January 22, 2021 - link
Bji, no, that is not how how engineering works. You need to know the failure limit on the minimum side. If your cooling system cannot consistently cool at least 65W, then your product will fail to meet specifications. That is a very important number for a system designer. Make a 60W cooling system around the 10700 chip and you'll have a disaster.You can always cool more than 65W and have more and/or faster turbos. There is no upper limit to how much cooling capability you can use. A 65W cooler will work, a 125W cooler will work, a 5000 W cooler will work. All you get with better cooling is more turbo, more often. That is a selling point, but that is it - a selling point. It is the the 65W number that is the critical design requirement to avoid failures.
edzieba - Friday, January 22, 2021 - link
Minor correction on " Never has been, never will be": TDP and peak package power draw WERE synonymous once, for consumer CPUs, back when a CPU just ran at a single fixed frequency all the time. It's not been true for a very long time, but now persists as a 'widely believed fact'.Something being true only in very specific scenarios but being applied generally out of ignorance is pretty common in the 'enthusiast' world: RAM heatsinks (if you're not running DDR2 FBDIMMs they're purely decorative), m.2 heatsinks (cooling the NAND dies is actively harmful, cooling the controller was only necessary for a single model of OEM-only brown-box Samsung drives because nobody had the tool to tell the controller to not run at max power all the time), hugely oversized WC radiators (from the days when rad area was calculated assuming repurposed low-density-high-flow car AC radiators, not current high-density-low-flow radiators), etc.
Even now "more cores = more better" in the consumer market, despite very few consumer-facing workloads spanning more than a handful of threads (and rarely maxing out more than a single core).
dullard - Friday, January 22, 2021 - link
I'll give you credit there. I should have said "not since turbo" instead of "never has been". Good catch. I wish there was an edit button.Spunjji - Friday, January 22, 2021 - link
What's really sad is that you apparently prefer to write a long comment trying to dunk on the author, rather than read the article he wrote for you to enjoy *for free*."I actually think that Intel went in the right direction with Tiger Lake"
You think poorly.
"Yes, TSMC has a fantastic node right now with lower power that AMD is making good use of. Yes, that makes Intel look bad. Lets clearly state that fact and move on."
Aaaand there's the motivation for the sour grapes.
dullard - Friday, January 22, 2021 - link
Spunjji, I must assume since you didn't have anything to actually refute what I said, that you have nothing to refute it and instead choose to bash the messenger. Thanks for backing me up!