How does the "Turbo Boost" on Coffe Lake Core i5-8400 work, and why?

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el.hombre.mo

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I don't mean physically or in a programming sense. I know next to nothing about building computers so I wouldn't understand most of it anyway. I am debating whether it would be better for me (and my wallet) to go with an i3-8100 or an i5-8400. The game I am most interested in building this computer for is Call of Duty: WW2

When I ask, "How does it work" I mean: Does the CPU detect how much power it needs and correct itself accordingly, or does it just boost up to max speed when 2.8ghz isn't enough? Or is it none of the above and I am completely misunderstanding the concept?

Does the Turbo Boost need to be turned on or activated for me to take advantage of it, or is it already on when I install it? i.e. if I install the i5-8400 and turn on the computer and try to play a game which requires (for example) a 3.8ghz processor to run smoothly, will it do that, or do I have to go in to some settings somewhere and make it do that?

What is the purpose of the Turbo boost mode? If the CPU will run at 3.8ghz without a problem why does the manufacturer set the base clock at 2.8ghz + optional 1ghz instead of setting it at 3.8 to begin with? If I want to build a computer for a game which needs 3.2ghz, would I not be better off simply buying a 3.2ghz processor?

I've heard that most games won't even make use of 6 cores, and that a lot of them are only designed to make use of 2. Is that true? How would that work; if I have a 3ghz cpu spread out between 6 cores and the game only uses 4 cores, do I effectively have a 2ghz cpu for that game?

And do I need any specific type of motherboard to be able to take advantage of the turbo boost mode or will any i5 (1151 socket) compatible motherboard be able to do that?

Sorry if I have asked some stupid questions but I want to fully understand this to the best of my ability. If anybody has answers to questions I didn't know to ask, I welcome them as well.
 
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why_wolf

why_wolf

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It is completely automated, you are not required to do anything to make it work. It just does.

They don't guarantee it can sustain at top turbo speed, hence the lower base speed. However with a decent 3rd party cooler it will maintain itself at top turbo speed no problem. This is more of an issue for laptops which have way worse thermals than a desktop.

You need to buy a motherboard that matches the required chipset generation of the CPU, they all support turbo it's a basic Intel function. Use PCpartpicker to avoid buying the wrong motherboard. This is extra confusing this generation as Intel didn't change the socket type, LGA 1151, for Coffee Lake. However Coffee Lake won't work with older 100/200 series motherboards, nor will Skylake/Kabylake work with the newer 300 series motherboards that Coffee Lake uses.

H & B motherboards are the basic no overclock motherboards, this is the kind you want. Z are the overclock motherboards, don't buy one unless you are using a K series CPU which allows for overclocking.
 
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TechyInAZ

TechyInAZ

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Don't be sorry, no question is dumb.

Intel Turbo Boost is designed to give you extra performance when an application requires a LOT of CPU resources (typically above 50% load on the CPU). So when your at very low CPU usages you'll be at 2.8ghz or lower to save power.

However the in the last 5 years the "base clock" has really not mattered much because when your at 100% CPU usage, your still using turbo boost unless your CPU is getting too hot.

So lets take the 8400 as an example:

2.8ghz = Only low load applications.

4ghz = When only a single core is loaded up

3.6-3.8ghz = When all 6 cores are loaded up.

So you'll always be above 3.2ghz when doing demanding stuff.
 
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Kasper Jorgensen

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The I5-8400 is a way better gamer CPU than the I3. The turbo boost will boost the CPU clock speed automatically if needed and depending on number of active cores.

Number of active cores - Max turbo boost clock
#1 - Max 4 GHz
#2 - Max 3.9 GHz
#3 - Max 3.9 GHz
#4 - Max 3.9 GHz
#5 - Max 3.8 GHz
#6 - Max 3.8 GHz
 
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Karadjgne

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Turbo is a variable. The cpu is set to run all of its cores at a specific speed, and not have heat issues with a stock cooler. What turbo does is when you use less than all cores, say 1 or 2 cores, the cpu has room to go faster (hotter) on those 2 cores and still stay inside limits. As you add core usage, the turbo slows down, so if 2x cores are 3.8,then 4x cores might be 3.6. So speed will change depending on usage, it allows maximum performance when the cpu isn't taxed hard. If all the cores were set at 3.8, using all cores would cook the cpu with the cheap cooler.
 
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Eximo

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What Intel is essentially saying is that the base clock is the guaranteed frequency of the CPU under a full load within the given power envelope. The various boost states apply to various numbers of cores. The top number usually referring to a single core, and increments down as the number of cores in use increases.

No action is required on your part, and the CPUs will work in any of the compatible motherboards available now (which are only the high end ones anyway).

Essentially if the CPU is not overheating it will run at boost clocks depending on the load. A game will tax one core pretty hard for the game engine and others as needed. It is true that many games are built for older hardware and two cores is really all that get utilized. Doesn't really matter that you have 6, but those two it uses (though it will load balance across many cores) will be able to run at the higher clock rates.

Finally clock speed can really only be used to compare chips of the exact same architecture. So the i5-8100 is slower overall than the i5-8400 or i5-8600k. You get what you pay for essentially.

Since you can only buy Z class boards right now, you can likely force the locked CPUs to run at their boost frequency all the time on all cores. You will likely need a better cooling solution then the one provided though. There is also some minor overclocking possible, but from what I have read, you might get 100Mhz or so out of it. Not really worth it.
 
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DRagor

DRagor

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No, with Turbo Boost it is actually opposite - the lesser number of cores game uses, the faster they will get.
 
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dark_lord69

dark_lord69

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i3-8100
i5-8400

Intel is trying to help a bit with the naming.
The 8 is the generation number. The last 3 digits are indicative of performance vs it's peers...
So
100 < 400

"Call of Duty: WW2"
The 8100 will meet minimum system requirements but the 8400 will meet the RECOMMENDED system requirements.

"Does the CPU detect how much power it needs and correct itself accordingly"
Yes, Turbo is enabled as needed when a CPU needs more speed.

"does it just boost up to max speed when 2.8ghz isn't enough?"
Yes, it will boost when the given clock frequency isn't enough for the workload.

"do you have to go into some settings somewhere and set your clock speed?"
Nope, it's built in and adjusts automatically on the fly as needed.

"What is the purpose of the Turbo boost mode?"
To consume less electricity when a computer doesn't need 100% of it's processing power.

"If the CPU will run at 3.8ghz without a problem why does the manufacturer set the base clock at 2.8ghz + optional 1ghz instead of setting it at 3.8 to begin with?"
Power saving...

"If I want to build a computer for a game which needs 3.2ghz, would I not be better off simply buying a 3.2ghz processor?"
Better off? Not necessarily.

"I've heard that most games won't even make use of 6 cores"
True.

"that a lot of them are only designed to make use of 2."
Most commonly, 2 - 4 cores depending on the game.

"How would that work; if I have a 3ghz cpu spread out between 6 cores and the game only uses 4 cores, do I effectively have a 2ghz cpu for that game?"
No, that's just not how it works. If a game uses 4 cores then 4 cores will be used at up to then max boost level. In the example you gave all 4 cores would be running at 3GHz (Assuming that is the CPU's max boost clock rate for 4 cores). 2 cores will be doing nothing or left to do windows background tasks.

"is it already on when I install it?"
Yep, you don't have to do ANYTHING.

"And do I need any specific type of motherboard to be able to take advantage of the turbo boost mode or will any i5 (1151 socket) compatible motherboard be able to do that?"
Any motherboard will allow boost, it's part of the CPU.
 
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hommelgaardkonstantin

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hommelgaardkonstantin

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Can someone help me I just built my i5 8400 I tried some games out and looked at task manager the cpu just says 2.80 ghz is it supposed so say 3.8 ghz or does it do it without showing anything? Would like to get an answer Thank you btw I’m new to computer I suck :( sorry
 
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Karadjgne

Karadjgne

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Most programs only read the digital id of the cpu it's way faster than trying to read any actual information. So since the cpu is officially labeled as 2.8GHz, that's what most programs will show. Cpu-z will show actual speed, at the time it's run, so to see your OC speeds or turbo speeds, you'll need to run cpu-z during a load. But as said earlier, the turbo speed responds to the amount of cores running, so a high core program will show a low turbo speed, a low core program will show closer if not max turbo.
 
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avenge

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It is not true that games don't use more than 2/4 cores. Most games from the last few years can use all of your CPU cores even if you have 6/12, 8/16 and etc. The problem is if they use cores effectively and it also depends on the GPU and resolution - the more powerful GPU will use more CPU power especially if you don't have any FPS cap. Although this is also very game dependent. Sometimes 4/4 core CPU won't be enough and you can have bottleneck and stutter. The best is at least 4/8 CPU.
 
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blaqqcat

Dec 3, 2018
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My 8400 used to do 3.9GHz when 1 or 2 cores were loaded. Now it doesn't anymore. When 1 or 2 cores are used, they jump to 3.8GHz max. ASRock Z390 ITX motherboard.
 
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mdd1963

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lee1302 said:
i have question i have i5 8400 stocked cooler with 2.8 ghz will overclocking help the games run better or stick to what it is?
Click to expand...

8400 is not really over clockable, having a fixed multiplier, but, some mainboards' BIOS settings allow to run all cores near or at turbo speed (MCE mode), which is almost the same principle as overclocking, as it does increase performance...

The 2.8 GHz alluded to is merely it's minimum base clock speed on all core operation, and typically it will normally operate at all cores nearer to 3.7-3.8 GHz, or , possibly even 4 GHz on an MCE-capable board Z370/390 mainboard with a good cooler.
 
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mdd1963

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The stock cooler might allow temps right near the throttle point (or so the internet/YOutube reviews claim), your results may vary depending on what core voltage is applied, what load is placed on the CPU, ambient temps, turbo speeds used on your MB/BIOS, etc...

I'd first see what temps occur under your gaming loads, fire up HWMonitor, game for 30 min, check HWMonitor results for peak core/package temps achieved...; if under 85C peak, probably as good as could be hoped for with Intel's somewhat marginal provided cooler.

Intel thinks the cooler is adequate, but, a few Youtuber Hardware Reviewers/enthusiasts certainly disagree...
 
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lee1302

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ive ran several titles and ive seen it go up to 80% stocked with crackdown 3 mwh re 2 remake but im only running on 8gb ram ddr 4 but im getting another 8gb ddr 4 ram todayi have gtx 1050ti oc 4gb uses motherboard power 75w
 
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