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i5 2500K still kicking !

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SentinelAeon

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Apr 2, 2020
Location
Europe
Hello, its 2020 and i am still using my beloved i5 2500K with 8GB 1333Mhz ram. Right now both on stock, i plan to overclock them and have a few questions:

1) PER CORE VS ALL CORE: this is what baffles me. Most ppl go for all core. But why ? I will give you an example. On same voltage i can do either all core 4.3Ghz or i can do per core where it will be 4.3Ghz when 4 cores are used, 4.4Ghz when 3 cores are used, 4.5Ghz when 2 cores are used and 4.6Ghz when only 1 core is used. Do you see why i think per core is better ? When all 4 cores are used, i will have 4.3Ghz in both cases. But lets say i use some strange app or game that only knows how to use 1 core. Well i will have 4.6Ghz then, which is 300Mhz more than if i used all core. So can u explain to me why in this case all core 4.3Ghz is better then the other option ?

2) RAM SPEED: I have 2x4Ghz 1333Mhz 1.5V kingston ram. In the past i tested it and at default 1.5V i had no problem running it at 1600Mhz, passed all tests. Now i am wondering, would it be safe to crank the voltage to 1.65V and try to reach 1866Mhz ? Is 1.65V OK or should i go only for 1.6V ? What if i cant reach 1866Mhz, is 1700Mhz an option and will still be better than 1600Mhz ? How will i know if i should opt for higher frequency or lower timings ?

3) OTHER: I use Asus P8Z77-V LX motherboard. Anything special i should know about, like some special settings i can set to reach higher OC at lower heat/voltage, etc. ? Any additional tips ?
 

EarthDog

Gulper Nozzle Co-Owner
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Dec 15, 2008
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Buckeyes!
1. You've got an ancient 4c/4t cpu... you want them all at their fastest speed. I can see staggering a cpu with a lot more c/t, but not yours. You want them all as fast as they will go together.

2. The ram will handle 1.65v, yep.overclocking ram will help, but not much, note.

3. Nope. Read our guide and give it a go... we're here to help!!!
 

trents

Senior Member
Joined
Dec 27, 2008
Whether you want to run with one fast overclocked core or four not so fast overclocked cores depends on what you mainly use the computer for.

You say with your RAM overclocked you "passed all tests". What kind of tests did you use? Personally, given the small amount of performance gain that running faster RAM gives, I would not go for overclocking to 1866/1.65 volts and risk damaging the RAM over time. Unless, that is, you don't mind putting out the bucks for new components and just want to do it for the giggles. Also keep in mind that increasing the RAM voltage will put extra strain on the CPU's IMC and that may have a negative impact on overclocking the CPU.
 
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SentinelAeon

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Apr 2, 2020
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Ok i will see how it goes with ram and will only go as high as 1.6V. As for components, well, i know there is a risk but i cant leave something at default without tweaking it, its the way i am.

IMPORTANT: I think you both misunderstood me as my question for point 1. Both settings will apply 4.3Ghz when all 4 cores are used. There is no difference in frequency when using all 4 cores. The only difference is that in first case, it will remain 4.3GHz even if 1 core is used. And in second it will apply a whooping 4.6Ghz when only 1 core is used. I tested it and it needs the same voltage for this. I guess its logical, since when 4 cores are used, frequency is same. And when only 1 core is used, it has got spare juice to pump 1 core very high. I hope i wrote it well this time, sorry for confusion :)
 

EarthDog

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I understood. :)

With only 4c/4t, multiple cores are being used at all times for the most part. It would be rare, desktop type things, for you to not use more than one core. That said, it doesn't hurt anything, but if all c/t can reach 4.6, why not is my question?
 

trents

Senior Member
Joined
Dec 27, 2008
Yes, I understood that from your initial post, except maybe the voltage being the same in both scenarios part.
 
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SentinelAeon

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Sadly i cant do all core 4.6Ghz. Just now after some problems with bios (OC options missing, had to use amiflash with all blocks checked to repair it -.-), i put it to optimized defaults. And then i remembered that golden rule from various 2500k OC pages and applied 4.5Ghz all core and 1.3V. Sadly, bluescreen in windows. Sure, i could play around with various settings to see if it helps, but for now i will try to make it 4.3Ghz all core and see how much voltage i need to make it stable and if my cooling is enough. If it is, i will then try all core 4.3Ghz and 1 core 4.6Ghz. And if i think i will have headroom i will push 4.4 or 4.5Ghz. But i doubt it, i OCed this proc before and never could go past 4.3Ghz on normal voltages, i clearly have a bad sample.
 

trents

Senior Member
Joined
Dec 27, 2008
Or you could decide what max core voltage you are willing to live with 24/7 and then clock up as far as you can on that. Don't forget to disable the power saving stuff in bios.
 
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SentinelAeon

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I wouldnt have a problem going to 1.4V 24/7 on vcore. The temps will be a problem. Right now my airflow isnt perfect in pc case, i plan to move to better case with better fans soon since i got all the things i need so no cost. But until then ....

I am running a test now, 4300Mhz all core, i set the voltage to 1.3V in bios. HWmonitor and cpu-z show 1.320V - 1.328V. I set CPU fan to 70% and 2 90mm system fans to 70%. After 35 minutes of running PRIME95 inplace test, the hottest core reached 68C. Which is ok u might say. But its not. First of all, when i play a game like dragon age 3 and that massive R9 390 works, the cpu temp is actualy about 7C hotter then under prime95 alone since the case is hotter. And second ... right now its 21C in my room. In the summer, temp in my room will be 28C or even more. If u put all that into account, that means 68C + 14C = 82C. And that isnt ok. The last time i was overclocking i think i found a sweet spot of 4.2Ghz all core, that allowed me to lower vcore enough to keep temps in check. I need to lower vcore until i get about 60C in inplace prime95. That will leave me just enough room for R9 390 and summer :)

I will keep playing with my system and let you know how it ends. Btw, just a funny video on how ram speed affects i5 2500k in some games. In some games difference between 1600 and 2133Mhz is quite big. I wish they would test 1333Mhz and 1866Mhz also :) Here is the video:

 

EarthDog

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That is terrible case airflow... typically game loads are nowhere near P95 loads... even with a GPU running in the same chassis.
 
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SentinelAeon

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I only have 2 92mm fans blowing out of the case and i make sure their speed during gameplay is only barely audiable. My next case will use 120 and 140mm fans. But still it will be made so i cannot hear the fans.

Btw i was playing around a bit with overclocking yesterday and it made me remember how bad my chip really is. Look at this. I tried:

1) 4.3Ghz 1.25V -> BSOD in prime95. Tried turning on every possible overclocking thing i found in guides, 1 by 1 and testing, no difference.
2) 4.0Ghz 1.20V -> BSOD in prime95 Tried turning on every possible overclocking thing i found in guides, 1 by 1 and testing, no difference.
3) 4.0Ghz 1.25V -> passed overnight inplace prime95.
 

trents

Senior Member
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Dec 27, 2008
I only have 2 92mm fans blowing out of the case and i make sure their speed during gameplay is only barely audiable. My next case will use 120 and 140mm fans. But still it will be made so i cannot hear the fans.

Btw i was playing around a bit with overclocking yesterday and it made me remember how bad my chip really is. Look at this. I tried:

1) 4.3Ghz 1.25V -> BSOD in prime95. Tried turning on every possible overclocking thing i found in guides, 1 by 1 and testing, no difference.
2) 4.0Ghz 1.20V -> BSOD in prime95 Tried turning on every possible overclocking thing i found in guides, 1 by 1 and testing, no difference.
3) 4.0Ghz 1.25V -> passed overnight inplace prime95.

In post #1 you were hitting 4.3 ghz on all cores. What happened? Has this deterioration in overclock ability resulted from the bios issues you describe in post #7? What is the make and model of the motherboard you are using? I'm a little confused now. You have gone from trumpeting the virtues of your old 2500k to calling it a dog.
 
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SentinelAeon

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Apr 2, 2020
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I am using Asus P8Z77-v lx motherboard. To be honest i wanted 4.5Ghz on all cores but voltage required is just crazy. Same with 4.3Ghz. I decided my goal right now is 4.2Ghz and then i will see how it handles in games and work, how high the temperatures get. I did about 30 minutes of dragon age 3 and contrary to what i mentioned earler - cpu temp was lower than on prime95. I will test the 4.2Ghz in real time scenarios (i got a couple of tests ready, writing down all data and i will share them when its finished).

Overclocking is fun and reminds me why i got into it in the first place, many years ago. Look at this settings and what it produces:

1) 4.2Ghz all core, vcore 1.335V, cpu LLC regulator: regular. STABLE. measured vcore: 1.256V - 1.328V
2) 4.2Ghz all core, vcore 1.250V, cpu LLC regulator: ultra high. STABLE. measured vcore: 1.256V - 1.272V

Now get this. At first i was like, why the hell is there extra cpu llc regulator option, if all it does is actualy increase vcore. Why 2 options. Well, the upper settings both produce about the same power usage, but look at the vcore voltage. The one with LLC regulator set to ultra high actualy fluctuates less. And what is even more interesting, in the first case, when you stress test the cpu, the vcore drops. But in second case, when you apply benchmark stress, the vcore actualy rises ! This is amazing and i would love to know why that happens.


The upper settings are the lowest that actualy produced stable overclock. I have been using intelburn test, only for stability. For temperature i will use prime95 and dragon age 3 and some x264 encoding/decoding. Real life scenarios. Ig it turns out that under all those scenarios i remain under 70C, i might go for 4.3Ghz. For more, i will have to wait for new case.

1.335V for stable 4.2Ghz. My cpu really isnt very good, as opposed to what OC other people get. And my vdrop is also big when im not using LLC regulator. My power suply seems to be doing ok, 12V line is 12.192V - 12.288V.
 

bmwbaxter

Joined
Jun 9, 2010
Vdroop is common when not using LLC. Especially on the motherboard you are using.
4.2ghz isn't a bad overclock for 1.25 vcore IMO. I wouldn't see you getting much more of an OC.
 
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SentinelAeon

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Apr 2, 2020
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I got some news, i will add data in next post. For now just 1 interesting thing. So, i OCed my memory to 1600Mhz 8-8-8-22. And booted memtest86 and memtest86+. Both passed numerous times, 1 of them was even tested overnight. No errors. Then i ran OCCT system stress. And it crashed after 5 minutes. Then i used that memtest windows app, opened 1 window for each thread, so 4 tests. And it crashed. Now im on 1600Mhz 9-9-9-22, totaly stable. Just wanted to let u know, kindof wierd that memtest86 said its stable :)
 

Tír na nÓg

Member
Joined
Sep 19, 2015
Just a couple of things. If you stay below 90c, you can push the before to 1.45v on load.
4.2GHz max OC for a 2500k seems really low.
I remember running my 3 2600k's in the 4.8/5GHz range, below 1.5v. they were Water cooled, but still...
 
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SentinelAeon

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Apr 2, 2020
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I am not sure i want to push further. Right now in OCCT full system stress i reach top temp of 75C, gaming in dragon age gives me max temperature of 69C. Ofcourse that is while keeping my system almost inaudiable. Anything else is just pure chaos. Also my cpu cooler is at its limits, changing fan from 50% to 100% nets me 1-2C degrees difference, if i increase case fans, a little more. I ordered new fans and will transfer my pc into a new case - now i have 2 92mm case vents on low rpm, in new case i will have 2 140mm and 1 120mm, on low rpm ofcourse, chaos, remember ?

Btw, just for the fun of it, today i measured the temperature of air right in front of the cpu fan and just in front of GPU fans. Now while my case temperature is usualy around 28C (7C above room temperature), the temperature infront of fans reached 34C. Considering my room is 21C, it got me thinking. What if i, by gods help, somehow made sure that air in front of gpu and cpu was close to 21C instead of 34c. Im not saying its possible, i just said i will try. Think tunnel. hint hint ? :)
 

trents

Senior Member
Joined
Dec 27, 2008
Just a couple of things. If you stay below 90c, you can push the before to 1.45v on load.
4.2GHz max OC for a 2500k seems really low.
I remember running my 3 2600k's in the 4.8/5GHz range, below 1.5v. they were Water cooled, but still...

Agreed. 4.5 ghz should be a piece of cake.