Question i5-9400f turbo instability

Jul 1, 2019
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Hi,

I've been planning on getting an i5 9400f, but I've read that if you lock the turbo boost to always on for Intel CPUs it can cause instability. Ive never done overclocking before, and I know that this isn't quite the same as overclocking, but I'm wondering if I just need a good cpu cooler to prevent any issues? I.e. as long as the CPU is at a low temp it'll be fine?
 
The instabilitynis caused by turning the clocks up but not being able to change the voltage.
What are you talking about? You don't need to change the volts to get the 4.1Ghz of the 9400f and unless the CPU will be running in a very hot country without any air conditioning it will be cool enough even with the stock cooler.

Locking all cores to the max boost is not overclocking at all,the max boost is the speed the CPU should would always run at ,the only reason it clocks down is because turbo (and all the rest) is a power savings feature, you don't need the performance you save energy.

The 3600 with overclocking loses a bunch of everyday performance to gain a bit of productivity performance,unless you need to do something like rendering it's useless.
 
4.1ghz is the max single threaded speed. It will never, ever, reach that on all cores. It simply isnt designed to do that from the factory.

Enabling mce runs the chip out of intel's specifications. It increases power targets and will allow the chip to turbo higher on all cores than default and sometimes lock it to the turbo speed, but you do need good cooling.

Heres what gamers nexus says "If multi-core enhancement is enabled by default, the CPU will operate out of specification in a few ways, potentially causing issues for users. One example would be BSODs or CTDs under full-Turbo conditions, but with incorrect voltage applied."
https://www.gamersnexus.net/guides/3268-multi-core-enhancement-and-core-performance-boost-testing

So yea, it can cause the system to be unstable and crash.
 
4.1ghz is the max single threaded speed. It will never, ever, reach that on all cores. It simply isnt designed to do that from the factory.

Enabling mce runs the chip out of intel's specifications. It increases power targets and will allow the chip to turbo higher on all cores than default and sometimes lock it to the turbo speed, but you do need good cooling.

Heres what gamers nexus says "If multi-core enhancement is enabled by default, the CPU will operate out of specification in a few ways, potentially causing issues for users. One example would be BSODs or CTDs under full-Turbo conditions, but with incorrect voltage applied."
https://www.gamersnexus.net/guides/3268-multi-core-enhancement-and-core-performance-boost-testing

So yea, it can cause the system to be unstable and crash.
You can't pick and choose only the parts that suit you...
Yes for a K CPU (that is a overclockable chip) and with a Z motherboard you will go beyond specs because that's what those CPUs and mobos are made for,4.7Ghz is not a safe clock without precautions, 4.1 are safe.
In theory, Intel’s i7-8700K should only be boosting to 4.7GHz when under limited-thread workloads, but not under a full 12-thread workload. As a move to further battle one another in effort to look “best” on performance charts, outside of memory timing tuning, motherboard vendors introduced a feature that automatically applies max single-core Turbo across all cores. This is typically named “Multi-Core Enhancement,” and is entirely a motherboard manufacturer initiative – at least, the default configuration of it most certainly is.

That’s where the controversy arises: If multi-core enhancement is enabled by default, the CPU will operate out of specification in a few ways,
 
Jul 1, 2019
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Hey guys, thanks for the responses.

I had a look around and found this: https://www.overclock.net/forum/5-intel-cpus/1727076-9400f-overclock.html

However, I changed my OC mode from normal to expert and this allowed to lock turbo boost across all cores. From there I disabled EIST and C-State, leaving Turbo Boost enabled.

In Windows I set power option to high performance (CPU min/max states at 100%) and now it runs at 3.9GHz 24/7. This increases the voltage to about 1.13 - 1.14, so I would not recommend this with just the stock cooler. All I did was swap out my 4790K/Z97/RAM from my prior setup, so I already had the H110i GTX, which keeps my 9400F @ 3.9GHz at no more than 65C when stress testing.
That voltage doesn't seem too high. I was planning on getting a Z390 Gaming Plus from MSI, if I get a non-stock cooler maybe I'll be ok.
 
Jan 24, 2019
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Hey guys, thanks for the responses.

I had a look around and found this: https://www.overclock.net/forum/5-intel-cpus/1727076-9400f-overclock.html



That voltage doesn't seem too high. I was planning on getting a Z390 Gaming Plus from MSI, if I get a non-stock cooler maybe I'll be ok.
yeah man i agree im getting a i5 9400f and already bought the msi mpg z390 board and with a good air cooler or a decent water cooler you can lock those boosts in just fine with no issues at all it really depends on the mobo used when turbo-ing the cpu a mobo like the b360 isnt that good for it but a z390 "made for overclocking" is perfectly fine for it if your looking for a good air cooler i'd go with the hyper 212 evo for about 35$ or for water cooling id go with the Cooler master, master liquid LC240E for about 70$ or so
 

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