In­tel 8th-gen Core i7 vs. 7th-gen Core i7 CPUS

PCWorld (USA) - - Contents - BY GOR­DON MAH UNG

IN­TEL’S 8TH-GEN CORE i7 COF­FEE LAKE LAKE HIS H IS A A MONSTROUSLY GOOD MONSTROUSLY GOOD CPU THAT’S FI­NALLY WORTH AN UP­GRADE.

Oh, In­ter­net. We know you’ve been throw­ing shade at In­tel’s 8th-gen 6-core Core CPUS since they were an­nounced ( go.pc­world.com/dbi9). In fact, we bet you’re snidely com­ment­ing in Youtube or Red­dit right now that the CPU is just an­other re-badge of the “same old thing.”

Well guess what? While it is es­sen­tially a de­riv­a­tive of the pre­vi­ous CPU, there’s a whole lot more to the 8th-gen Core i7 than you think. It’s enough of a dif­fer­ence, in fact, that it’s prob­a­bly one of the rare times we can say it may be worth up­grad­ing over the pre­vi­ous CPU gen­er­a­tion. So yeah, that means it’s a big deal. We’ll ex­plain why—and show you bench­marks to prove it—right here.

WHAT EX­ACTLY IS 8TH-GEN CORE?

First, we had 8th-gen Core i7 “Cof­fee Lake S” ( go.pc­world.com/ clks) for desk­tops.

Then we had 8th gen Core i7 “Kaby Lake R” ( go.pc­world.com/ klkr) for ul­tra­portable lap­tops. Why it’s called Kaby Lake R in­stead of Cof­fee Lake U we don’t know.

Now, we fi­nally get 8th-gen Core i7 “Cof­fee Lake H” chips for larger lap­tops and gam­ing lap­tops. And yes, you’d be kinda right if you said that 8th-gen Cof­fee Lake is largely an im­proved 6th-gen Sky­lake CPU, first in­tro­duced to lap­tops in late 2015.

Along the way though, In­tel has made many im­prove­ments. The 7th-gen Kaby Lake’s video pro­cess­ing en­gine, for ex­am­ple, was greatly im­proved, and it gen­er­ally ran at higher clock speeds than 6th-gen Sky­lake could. With Cof­fee Lake, In­tel takes the ma­ture 14nm process and ten­der­izes the hell out of it, enough to de­serve the 8th-gen “14++” moniker.

HOW WE TESTED

Un­like re­mov­able desk­top CPUS, where you can con­trol just about all of your vari­ables such as cool­ing, power, mem­ory, and

stor­age, lap­top CPUS are gen­er­ally to be treated as en­tire pack­ages, be­cause they’re sol­dered to the moth­er­board.

De­sign de­ci­sions by the lap­top maker also greatly im­pact per­for­mance. Cer­tain ven­dors may tune for all-out per­for­mance, while oth­ers may ratchet things back to con­trol the fan noise. All this, of course, is in­flu­enced by the cool­ing in the lap­top, which is of­ten in­flu­enced by the sheer size of the chas­sis.

For this shootout, we de­cided to com­pare the 6-core MSI GS65 Stealth Thin ( go.pc­world. com/mgs5) with the thick-and-large 17-inch Len­ovo Le­gion Y920 (re­view forth­com­ing on Pc­world.com). The Le­gion Y920 is rolling a quad-core Core I7-7820HK CPU. Be­cause the CPU is un­locked and a showcase fea­ture of it is over­clock­ing, we also tested the Core I7-7820HK in the Le­gion Y920 with the over­clock switch en­gaged. Rep­re­sent­ing the pre­vi­ous gen­er­a­tion is the Asus ROG Ze­phyrus GX501 ( go.pc­world.com/g501). The ROG Ze­phyus GX501 is a 17-inch lap­top, but ul­tra-thin and equipped with the pop­u­lar 7th gen quad-core Core I7-7700HQ CPU.

PER­FOR­MANCE

Keep in mind that the three lap­tops used for this CPU roundup all fea­ture dif­fer­ent GPUS: The Len­ovo Le­gion Y920 has a Ge­force GTX 1070, the Asus ROG Ze­phyrus GX501 has a Ge­force GTX 1080 Max-q GPU, and the MSI GS65 Stealth Thin uses a Ge­force GTX 1060.

Due to the dis­par­ity of the GPUS and their out­size in­flu­ence on graph­ics, we did not delve into graph­ics per­for­mance for this re­view. You should re­ally make your graph­ics buy­ing de­ci­sion based on other fac­tors, not the CPU.

CINEBENCH R15 PER­FOR­MANCE

The first re­sult is Cinebench R15. It’s a bench­mark built around Maxon’s Cine­ma4d en­gine and fa­vors more cores and more cores. No sur­prise, the in­crease from 4 to 6 cores yields a pretty huge per­for­mance boost. Although Cinebench R15 is mostly a pre­dic­tor of multi-threaded per­for­mance, you should ex­pect to see gen­er­ally sim­i­lar re­sults in other ap­pli­ca­tions that will ac­tu­ally use all 12 threads or 6 cores of the Core i7-8750h CPU.

The thing is, not all ap­pli­ca­tions are mul­ti­threaded. In fact, we’d ar­gue few are so ef­fi­cient as to give you the same re­sults you see above. It’s prob­a­bly far more im­por­tant for those not ren­der­ing 3D, edit­ing video, or do­ing other in­ten­sive con­tentcre­ation tasks to look at sin­gle-threaded per­for­mance of a lap­top CPU.

To gauge that, we also ran Cinebench R15 us­ing a sin­gle CPU thread. Pre­dictably, things even up quite a bit, but the newer 8th-gen CPU is still leader of the pack. In fact, even against the over­clocked Core I7-7820HK, it’s ahead by more than 7 per­cent. And against the far more “nor­mal” Core I7-7700HQ in the Asus ROG Ze­phyrus GX501, you’re look­ing at a 13-per­cent in­crease in per­for­mance.

CORONA 1.3 PER­FOR­MANCE

Our next test is the Corona 1.3 bench­mark.

It’s built on the Corona Pho­to­re­al­is­tic ren­derer

for Au­todesk’s 3ds Max. Like Cinebench and most ren­der­ing apps, it fa­vors more cores. The re­sults con­firm what we saw in Cinebench, which is sim­ple math: 6 cores are bet­ter than 4.

BLENDER PER­FOR­MANCE

Our last ren­der­ing bench­mark uses the free Blender app to mea­sure how long it takes to ren­der a sin­gle frame us­ing Mike Pan’s pop­u­lar BMW bench­mark file. The per­for­mance isn’t quite as dra­matic as Corona’s, Cinebench’s, or other ren­der­ing bench­marks we’ve tried, but it’s still a very de­cent bump.

So why does Blender put th­ese CPUS much closer than Cinebench, Corona, or V-ray? (We ran V-ray but didn’t bother with show­ing you a chart be­cause it’s pretty much a clone of Corona and Cinebench’s re­sults). We be­lieve it’s be­cause of the length of the ac­tual tests. Cinebench and Corona run in a minute or two, while the BMW work­load can take around 10 min­utes.

As you heat up a lap­top CPU, the clock speed be­gins to drop slowly to man­age the heat. On the Core i7-8750h, its per­for­mance ad­van­tage over quad-cores mostly de­rives from core count and clock speed. On longer loads, most of the clock speed ad­van­tage will burn off.

This is also likely why the Len­ovo’s de­fault speeds on the Core I7-7820HK are rather unim­pres­sive, while its over­clocked per­for­mance gets much closer to the Core i7-8750h’s. Still, chalk this up in the win col­umn for the 8th-gen Core i7-8750h.

EN­COD­ING PER­FOR­MANCE

For an en­cod­ing test, we take a 30GB 1080P MKV file and transcode it us­ing Hand­brake 9.9 and the An­droid Tablet pre­set. Like the Blender BMW test, it typ­i­cally takes 45 min­utes or so to fin­ish on a quad-core lap­top, largely nul­li­fy­ing any high clock speed ad­van­tage. This par­tic­u­lar test shows just how valu­able the ex­tra cores are, be­cause even with its high clock ad­van­tage gone, it fin­ishes the en­code in about 33 min­utes ver­sus the 46 min­utes of the Core I7-7700HQ.

COM­PRES­SION PER­FOR­MANCE

We’ll wrap this up by look­ing at the per­for­mance of the CPUS in WINRAR’S in­ter­nal com­pres­sion bench­mark. The first re­sult is the sin­gle-threaded per­for­mance of the lap­tops CPUS. The higher-clock speed of the Core i7-8750h again shines through, but like the sin­gle-threaded re­sults of Cinebench, it’s ac­tu­ally pretty close.

Oddly, the Core I7-7700HQ of the Asus ROG Ze­phyrus GX501 un­der­per­formed here. We reran the test mul­ti­ple times and the re­sults didn’t vary so it’s not a mis­take. With the Core I7-7700HQ per­form­ing quite well ev­ery­where else, we sus­pect this may be the odd mem­ory con­fig­u­ra­tion of the unit we tested: 24GB. Asus used a 16GB DIMM and an 8GB DIMM, which means the mem­ory band­width isn’t al­ways run­ning in dual-chan­nel mode. Be­cause WINRAR does fa­vor in­creased mem­ory band­width, this mem­ory con­fig­u­ra­tion may have been enough to hurt it.

Run­ning WINRAR in its multi-threaded mode, the re­sults moved back to what we ex­pected. Again, sim­ple math pre­vails on multi-threaded tests and 6 > 4. Even the

Core I7-7700HQ in the Asus was back to nor­mal.

PER­FOR­MANCE ANAL­Y­SIS

So let’s break down the ad­van­tage of the

Core i7-8750h in a lit­tle more de­tail. As you know, more cores is bet­ter, but Core i7-8750h also runs at far higher clocks most of the time. Not all apps will use the max­i­mum amount of cores on a CPU, nor will they all use only a sin­gle thread.

To dive into that, we reached for Cinebench R15 again and ran the test with it set to use from 1 to 12 threads on the Core i7-8750h (green bars on the chart, next page) and from 1 to 8 on the Core I7-7700HQ (blue bars). We used the Core I7-7700HQ be­cause this is the chip that will most closely com­pete with the Core i7-8750h.

One prob­lem with this chart is it doesn’t scale with the ac­tual per­for­mance gain. In the chart at the bot­tom of the next page, we’ve cal­cu­lated the ad­van­tage the 8th-gen Core i7-8750h has over the 7th-gen Core I7-7700HQ. Ob­vi­ously, most of the per­for­mance is on the right side of the chart, be­cause hav­ing six cores is al­most al­ways go­ing to be bet­ter (if they’re in the same fam­ily.) But there’s a very solid dou­ble-digit per­for­mance gain on the lighter loads, too.

Be­cause the Cof­fee Lake H is es­sen­tially the same micro-ar­chi­tec­ture as Kaby Lake H, the gains are mostly In­tel’s (and OEMS’) com­fort lev­els with push­ing the chips to higher clock speeds. To get a lit­tle more insight into just how much of an ad­van­tage that is, we re-ran Cinebench R15 us­ing loads while in­creas­ing the amount of threads the pro­gram used. We recorded the rough clock speed 20 sec­onds into the bench­mark. We say “rough” be­cause it’s not ex­actly 100 per­cent re­peat­able, and is a stop­watch-based and Mark I eye­ball record­ing of the re­sults.

Still, the data is plenty use­ful. As you can see, the Core i7-8750h (yel­low line be­low) is cook­ing along at far higher clock speeds on lighter loads than the Core I7-7700HQ is. You can also see that even though there is no clock speed ad­van­tage on the right side of the chart due to the in­creased ther­mal load, it doesn’t mat­ter be­cause the Core i7-8750h can call for backup from those two ex­tra CPU cores.

VER­DICT

We’ve all rightly be­come cyn­i­cal about In­tel’s lap­top CPUS and the “gen­er­a­tional” tag. Over the last few years, there have been few to no

rea­sons to up­grade. For ex­am­ple, if you bought a 5th-gen Core i7, you re­ally had no rea­son to up­grade to a 6th-gen Core i7. Af­ter all, all you’d re­ally get is a 6- to 7-per­cent per­for­mance bump. So yeah, yawn.

For the first time in for­ever, though, there’s an ac­tual rea­son you might need, might ac­tu­ally want, to up­grade from the pre­vi­ous gen­er­a­tion.

For ex­am­ple, if you just bought a 7th-gen Core i7 to do video edit­ing, ren­der­ing, or any­thing that truly needs more per­for­mance, we can hap­pily say tak­ing a loss on that old lap­top for a new 8th-gen Core i7 is fi­nally worth it. You’ll get rea­son­able per­for­mance bumps on lighter loads and huge per­for­mance gains on the heavy loads.

Not ev­ery­one needs it. For push­ing Word and a browser all day—stick with what you have. But if you bought a Core i7 lap­top to get real work done, the 8th-gen Core i7 is a wor­thy up­grade that is long over­due.

For the first time in for­ever, though, there’s an ac­tual rea­son you might need, might ac­tu­ally want, to up­grade from the pre­vi­ous gen­er­a­tion.

AN UP­GRADE THAT’S FI­NALLY WORTH IT

The 6-core 8th-gen Core i7-8750h in the MSI GS65 Stealth Thin eas­ily schools larger lap­tops with 7th-gen CPUS in them.

Con­sumer Re­ports pulled its rec­om­men­da­tion of the Sur­face Lap­top, even though the note­book wasn’t cov­ered in the sur­vey.

Thanks to the higher clock speeds of the 8th-gen Core i7, it has a dou­ble-digit edge against most stan­dard CPUS.

Even the over­clocked Core I7-7820HK can’t stand against the lat­est 8th-gen Core i7-8750h, be­cause of the sim­ple math of 6 cores are bet­ter than 4.

The BMW work­load in Blender takes longer to run than most ren­der­ing bench­marks, which neu­tral­izes the high clock speed ad­van­tage of the Core i7-8750h.

The Corona Ren­derer is a photo-re­al­is­tic ren­derer that con­firms more cores mat­ter when you’re do­ing ren­der­ing.

More cores help the Core i7-8750h fin­ish our en­code in about 33 min­utes com­pared to 46 min­utes of a Core I7-7700HQ. That’s a sig­nif­i­cant per­for­mance ad­van­tage.

In sin­gle-threaded per­for­mance every­thing was as ex­pected ex­cept for the oddly low per­for­mance of the Core I7-7700HQ.

More cores are bet­ter, WINRAR says, and the Core i7-8750h has more cores.

We use Cinebench R15 and limit the threads to try to suss out how well the CPUS per­form on a given load.

You can see the clock speed ad­van­tage the Core i7-8750h has over the Core I7-7700HQ on lightly threaded apps. Even though there’s no mega­hertz dif­fer­ence on the heavy loads it doesn’t mat­ter be­cause the 8th gen part has more cores to use.

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