Gear 1 can Lead to Performance Loss on Intel "Rocket Lake" 11th Gen Processors

[btarunr]

In the course of our Core i5-11400F "Rocket Lake" processor review, we discovered that the Gear 2 memory mode has the potential to offer higher performance than Gear 1. The Gear 1 mode runs the memory frequency and memory controller frequency in 1:1 sync, while the Gear 2 mode runs them at 1:2, meaning that the memory controllers run at half the memory frequency, allowing you additional memory overclocking headroom. At lower, more stable, memory frequencies, it should be logical to use Gear 1. Our testing springs some surprising results.

Overall, a stock Core i5-11400F paired with DDR4-3733 MHz memory, was found to be 1.5% faster with Gear 2, when averaged across all our CPU tests, compared to Gear 1 at the same 3733 MHz frequency. Gear 2 was 3.42% faster in Cinebench R23 multi-threaded, and a staggering 6% in MySQL. Across rendering and media workloads that scale across all cores, we find Gear 2 faster by 1-3%. It's only with less parallelized workloads such as gaming, where we see Gear 2 lag behind Gear 1, though not by much. In our i5-11400F review, we show that by running your processor in Gear 2, you're making your memory controllers pull less power, freeing up power budget for the CPU cores, translating into the nT performance gains we see here. We discovered that the uncore can pull anywhere between 5 to 10 W more power in Gear 1 mode. This is valuable power eating into the already constrained power-budget of this 65 W TDP chip.

Read the Intel Core i5-11400F TechPowerUp Review



This behavior wasn't spotted in our launch-day i5-11600K and i9-11900K reviews; as the i5-11400F is our first Rocket Lake with a 65 W TDP. We expect the disparity between Gear 2 and Gear 1 at stock settings to only grow wider with higher core-count 65 W models, such as the Core i7-10700/F and the i9-11900/F. Gear 1 claws its way back to the top when you engage power limit overrides offered by motherboards. These overrides vary from motherboard to motherboard, but they generally free up more power budget for your CPU cores to sustain their boost frequencies better. For more data and commentary, be sure to catch our Core i5-11400F review.

View at TechPowerUp Main Site

 

[Aranarth]

Talk about "bleeding edge"!

Death by a thousand (power budget) cuts.

 

[Kohl Baas]

Gears of poWar.

 

[ZoneDymo]

I dont even get this new gear nonsense

 

[FlanK3r]

this is a litle "noobish"
Because for example Gear2 3733Mhz 14-14-14-31-2T U need at least 4533 MHz cl20 Gear2 to be better (4266 c19 is similar)

 

[shadow3401]

Ooof even more power (and higher temperatures) for slightly lower performance. Rocket lake == P4 Prescott / AMDs bulldozer.

 

[qubit]

That's interesting. It stands to reason that running the memory at a 1:1 ratio would result in faster performance than half speed, but we don't quite see that.

As your article points out, what skews it is power draw, which is being constrained to keep within the rated specs. Once that constraint is lifted, the 1:1 ratio wins out, as expected. It makes sense that the higher performance mode would use more power.

Intel really needs that 10nm node badly so they won't have to use these power-limiting compromises quite so obviously.

 

[tabascosauz]

The title technically isn't...wrong, per se, but it's kinda obvious given how power limits work on any locked Intel chip or any PPT-limited AMD chip since 2019.

You can probably get the same result on Ryzen by artificially running 1066MHz Infinity Fabric @ 0.9V VSOC where you save like 10W on SVI2 SOC power draw compared to 1866MHz 1:1 IF @ 1.1V VSOC. Like, yeah, you get 10W more to invest into the cores (if not already current, temp or voltage limited) and will probably get slightly better boost performance out of strict CPU benchmarks, but people don't build new 11th gen computers to run CPU benchmarks 24/7 at stock settings and nothing else.

In return, running Gear 2 or low IF speed both get you doodoo performance in 99% of everything else outside of CPU benchmarks, so is it really "performance loss"? It's not even a revelation that's useful to overclockers because 1) 11400F isn't winning any races regardless of what you do 2) power limit is not an issue on anything that isn't locked 3) power limit isn't even an issue on the 11400F as long as you remove them.

So basically, "Gear 1 can lead to performance loss" is about the same as saying "1900MHz+ IF can lead to performance loss". Both technically true to some extent, and both misleading and benefiting precisely nobody.

 

[moproblems99]

In return, running Gear 2 or low IF speed both get you doodoo performance in 99% of everything else outside of CPU benchmarks, so is it really "performance loss"?

Hey, if some cheap ass was running a sql farm in might make sense.

 

[Tomgang]

A more fitting name than rocket lake, would be dead lake. I feel somehow rocket lake is DOA.

And now it seems what's supposed to be the best performance setting is the worst of the two gears.

14 nm really is on its last leg. Imagine if alder lake end up as 14nm as well.

 

[Wirko]

The title technically isn't...wrong, per se, but it's kinda obvious given how power limits work on any locked Intel chip or any PPT-limited AMD chip since 2019.

You can probably get the same result on Ryzen by artificially running 1066MHz Infinity Fabric @ 0.9V VSOC where you save like 10W on SVI2 SOC power draw compared to 1866MHz 1:1 IF @ 1.1V VSOC. Like, yeah, you get 10W more to invest into the cores (if not already current, temp or voltage limited) and will probably get slightly better boost performance out of strict CPU benchmarks, but people don't build new 11th gen computers to run CPU benchmarks 24/7 at stock settings and nothing else.

In return, running Gear 2 or low IF speed both get you doodoo performance in 99% of everything else outside of CPU benchmarks, so is it really "performance loss"? It's not even a revelation that's useful to overclockers because 1) 11400F isn't winning any races regardless of what you do 2) power limit is not an issue on anything that isn't locked 3) power limit isn't even an issue on the 11400F as long as you remove them.

So basically, "Gear 1 can lead to performance loss" is about the same as saying "1900MHz+ IF can lead to performance loss". Both technically true to some extent, and both misleading and benefiting precisely nobody.

That's all technically correct. It's just that ... we're not all overclockers. Of those who build a PC with an i5-11400F for 170 EUR, how many will spend a considerable sum for an aftermarket cooler (anything for ~40 EUR being barely better than the stock cooler) and try to test the limits of the CPU? For those who don't, a two-gear "gearbox" might be useful sometimes, and it surely doesn't hurt to have it.

 

[tabascosauz]

That's all technically correct. It's just that ... we're not all overclockers. Of those who build a PC with an i5-11400F for 170 EUR, how many will spend a considerable sum for an aftermarket cooler (anything for ~40 EUR being barely better than the stock cooler) and try to test the limits of the CPU? For those who don't, a two-gear "gearbox" might be useful sometimes, and it surely doesn't hurt to have it.

So...essentially you don't disagree with anything I said?

Gear 2 is specifically for overclockers. Period. It's what allows the 11th gen IMC to outperform pretty much everything on the market except for *maybe* Renoir/Cezanne.

Do you think the average user will go into their BIOS to enable Gear 2 at mundane speeds just so they can gain 2% extra performance in rendering, while losing 4% fps in all their games? Read the review, there is literally no benefit to this whole running Gear 2 to get a tiny bit more boost shenanigans. It's exactly the same shit as intentionally crippling Infinity Fabric to gain a few extra MHz in CPU benchmarks.

And once the PL1 limit comes off, Gear 1 goes right back to being on top. The people that can understand what Gear 2 is, most likely aren't the kind of people leaving the stock PL1 limit in place.

 

[W1zzard]

Gear 2 is specifically for overclockers

You are aware that you can't run DDR4-3800 on Gear 1 and have to use Gear 2, because the MC can't handle it ?

 

[Wirko]

So...essentially you don't disagree with anything I said?

Gear 2 is specifically for overclockers. Period. It's what allows the 11th gen IMC to outperform pretty much everything on the market except for *maybe* Renoir/Cezanne.

Do you think the average user will go into their BIOS to enable Gear 2 at mundane speeds just so they can gain 2% extra performance in rendering, while losing 4% fps in all their games? Read the review, there is literally no benefit to this whole running Gear 2 to get a tiny bit more boost shenanigans. It's exactly the same shit as intentionally crippling Infinity Fabric to gain a few extra MHz in CPU benchmarks.

And once the PL1 limit comes off, Gear 1 goes right back to being on top. The people that can understand what Gear 2 is, most likely aren't the kind of people leaving the stock PL1 limit in place.

I mostly agree, maybe I agree less about the target audience.
I'm referring to the review summary on page 23 here: in Gear 2, you lose less than 2% in games, except at 720p. The total "performance per dollar" is higher by 1% for Gear2, with default power limits in place.
In web browsing, compiling, ML, compression, encryption, you mostly gain something between zero and ~4%. So it's a small margin either way.
The default for i5 and i7 chips is going to be Gear 2 anyway, and it looks sensible, at least for the 11400F.

So yes, Gear 2 is aimed at memory overclockers, but it can also bring a performance advantage wherever the power budget is tight (limited not by PL1 setting but by the actual cooling solution). Every watt saved by the MC counts - in Rocket's case, the difference between gears is an incredible 9W on idle, no overclocking involved! (And that's almost as much as a Haswell mini PC consumed on idle in 2014.)

This is why I believe we'll see two gears in Alder Lake as well - think about notebooks and their 15W - 45W power limits, which include the IGP.

 

[tabascosauz]

You are aware that you can't run DDR4-3800 on Gear 1 and have to use Gear 2, because the MC can't handle it ?

Not sure where I said 3800 specifically for Rocket Lake, but point taken - a bad statement on my part. Still, I did say "mundane speeds".

The default for i5 and i7 chips is going to be Gear 2 anyway, and it looks sensible, at least for the 11400F.

This is why I believe we'll see two gears in Alder Lake as well - think about notebooks and their 15W - 45W power limits, which include the IGP.

True, default is Gear2. Which really begs the question how Intel could turn a 10%+ IPC increase into worse gaming and application performance than its predecessor.

I dunno if that's true about mobile - it's Superfin, better binned, and LPDDR4x seems to mitigate this problem. Perhaps the excessive Gear1 power consumption on RKL is more due to crappy backporting, 14nm, and the extremely tortured system agent. Also, some Z590 motherboards are defaulting to extreme levels of Auto VCCSA, didn't see anything in the review confirming that's not the case on the Hero.

Speaking of crappy backporting, even the midrange Coffee Lake chips could do ballpark 4000MT/s. Gear 2 did what was expected of it (raise the ceiling up significantly in the 5000-6000MT/s range), but wtf did they do to the IMC that the 1:1 limit in the 3000-4000 range is even lower than chips from 3 generations ago?

 

[Metroid]

Fail!!!!!

 

[nguyen]

How about Gear1 vs Gear2 at 3200MT/s? high speed DDR4 are still expensive and I wouldn't want to overspend on DRAM for budget build.

 

[watzupken]

I am not sure if the chip really utilises 65W as per TDP. If it really sticks to the 65W TDP, or even close and still able to maintain competitive performance, I think its a miracle chip from Intel.

 

[nguyen]

I am not sure if the chip really utilises 65W as per TDP. If it really sticks to the 65W TDP, or even close and still able to maintain competitive performance, I think its a miracle chip from Intel.

Well Intel 10th gen is still very competitive in the laptop market, with the 10870H winning against 5800H in a lot of games, probably due to 16lanes of PCIe vs 8lanes on Cezanne.
Intel is just being cheapskate with their silicon die size and decide to push higher voltage and less cores, kinda like AMD with the 6700XT. If the 11900K had 10cores working at lower freq/voltage, it's efficiency would look way better in paper.

 

[tabascosauz]

Well Intel 10th gen is still very competitive in the laptop market, with the 10870H winning against 5800H in a lot of games, probably due to 16lanes of PCIe vs 8lanes on Cezanne.
Intel is just being cheapskate with their silicon die size and decide to push higher voltage and less cores, kinda like AMD with the 6700XT. If the 11900K had 10cores working at lower freq/voltage, it's efficiency would look way better in paper.

Intel has no qualms about making a bigger 14nm die, but Rocket Lake literally has no room to get bigger. The ringbus was already taxed by the 10900K, the 11900K core-to-core is now double that of Zen 3 (intra-CCX), you want more cores and you'll have to go mesh which makes no sense from R&D for a one-off MSDT half-generation. And the Cypress Cove cores are huge [piles of shit]. Extend the top of the RKL die and you'll hit the new row of capacitors. Extend the bottom of the die and it'll contact the heatspreader.

Where Intel fucked up was for some reason undoing the Comet Lake die thinning/better STIM/thicker heatspreader. They literally erased last gen's thermal innovations that made it run relatively cool, and now it's back to the infernal 9900K package except this time it's even hotter. There's no way that stock AVX512 would be above 100C if Intel had pulled out all the stops like they did Comet Lake. derbauer already tested the delidded 11900K and iirc it was a double-digit temp difference. The whole thing just screams half-assed product.

 

[Prima.Vera]

So you are telling me that with this crap garbage Gen 11 CPUs, having RAM faster than 3600Mhz actually decreases performance?!?
Things are getting better and better.

 

[ratirt]

Intel is just being cheapskate with their silicon die size and decide to push higher voltage and less cores, kinda like AMD with the 6700XT. If the 11900K had 10cores working at lower freq/voltage, it's efficiency would look way better in paper.

I understand you compare cpu to cpu like 10th to 11th gen Intel but bringing AMD GPU into this? The GPU is same arch like every other 6000 series not like 10th and 11th gen Intel CPUs. The voltage is higher due to, for example, silicon quality and/or clocks being pushed a bit higher to compensate but it doesn't mean they cheapskate on the 6700xt GPU. It is a cut-down version of the same 6000 series GPUs

If the 11900K had 10cores working at lower freq/voltage, it's efficiency would look way better in paper.

Yeah. Ifs and butts... on paper, if the 11900K had 16 core it would have been even a better CPU but it isn't for a reason and Intel couldn't do anything about it because it is way larger than 10th gen equivalent and with the 10th gen 10900k Intel could max it out at 10 cores only. If Intel lowered frequency on the 11900K the gap between the 11900K and 10900K would have widened even more in favor of the 10th get CPU even if both have 10cores.

 

[W1zzard]

Not sure where I said 3800 specifically for Rocket Lake, but point taken - a bad statement on my part. Still, I did say "mundane speeds".

You are absolutely right of course when you say "overclocking", which it technically is, just wanted to make sure you are aware at how lousy speeds Gear 2 has to be enabled.

I am not sure if the chip really utilises 65W as per TDP. If it really sticks to the 65W TDP, or even close and still able to maintain competitive performance, I think its a miracle chip from Intel.

Of course it does. It will reduce CPU clock until it reaches 65 W

First chart on this page, just with different values of course: https://www.techpowerup.com/review/intel-core-i9-10900k/18.html

 

[stimpy88]

Good article! At least now I understand why Intel has added this gear mode in the first place.

Intel is so against the wall that they can't run the memclock at full speed when using fast memory, due to the ancient manufacturing process they are forced to use, the cores need every Watt they can get their hands on just to offer almost AMD like performance!

At this rate, I should look forward to next years Intel 6 core 14nm+++++++ flagship going against a Zen4 CPU, if AMD even bother to make a 6 core variant.

 

[Wirko]

Speaking of crappy backporting, even the midrange Coffee Lake chips could do ballpark 4000MT/s. Gear 2 did what was expected of it (raise the ceiling up significantly in the 5000-6000MT/s range), but wtf did they do to the IMC that the 1:1 limit in the 3000-4000 range is even lower than chips from 3 generations ago?

Hah, yes, exactly.

It's unfortunate that very few reviewers include idle power measurements - they are quite revealing. Apart from TPU, I only know of Hexus, and their numbers are similarly scary (i9-11900K on idle, which they only measured in Gear 1, vs. previous gen).