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Overclocking i5 2500k For First Time

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April 8, 2011 8:36:03 PM

Hi Guys,

I overclocked my i5 2500k and I want advice. I want my cpu perform faster in games. Note that currently I didn't buy any cpu cooler, It's just the stock cooler.
I am not sure how much should I oc, as for now I have oc'ed to 4GHz ( TurboBoost )

Mobo is Gigabyte
I followed some difference guides and I come up with these values :

CPU Clock Ratio : 33
Advanced
---------------
Internal CPU PLL OVervoltage : Auto
Real-Time Ration Changes In OS : Disabled
Inter Turbo Boost : Enabled
Turbo Ratio #1-4 : 40
Turbo Power Limit : Auto
Core Current limit : Auto
CPU Cores enabled : All
Bi-Directional Prochot : Auto
everything else : Disabled
---------------
BCLK/DMI/PEG clock control : Disabled
XMP : Disabled
SPD : Auto

Voltages
-----------
CPU Vcore : 1.250V
QPI/Vtt Voltage : 1.120V
System Agent Voltage : 1.135V
Dram Voltage : 1.660V


I run Prim95 for a few minutes and the temp max were ~75 ( Is it normal ? )

I think the voltages are not correct (Maybe too much ?)
Do I have to disable the TurboBoost and just the Multiplier itself ?

Waiting for your advices
a b à CPUs
a b K Overclocking
April 8, 2011 8:47:12 PM

All you should have to worry about when overclocking the 2500k is the CPU Vcore voltage. Instead of using turbo, I would rather try disabling turbo and up the CPU Clock ratio to 40 and check if you are stable. This does work though, I don't actually have a 2xxxk to play with, so I don't know if all 4 cores are turboing up to 4ghz.

Those temps might be a little too much for the proc, since it will most likely climb into the 80's if you kept P95 on longer. If the system is stable after a few minutes of Prime 95, then I would try to lower your Vcore voltage as much as possible until it starts failing Prime 95. Then raise the voltage a little bit and test stability for a few hours; I would run Prime 95, Intel burn test, and OCCT just to check stability for several stress test programs.
April 9, 2011 3:01:30 AM

I think you may need a better cooler if you want lower temps,1.25 volts is low already for the over clock.
I have 1.32 voltage for 4.5gz ,my temps on a Corsair h70 never go past mid 60's on prime95.
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April 9, 2011 3:13:55 PM

Yeah you are right the temps are not good, Tomorrow I'll buy a cooler. Anything will do ?
April 9, 2011 3:18:21 PM

Hyper 212+ is most common. Mine gets me to 4600MHz at 1.38v at upper 60's/lower 70's in IBT/8 threads....
a c 96 à CPUs
a c 228 K Overclocking
April 9, 2011 3:25:08 PM

As already stated, get a better cooling solution for overclocking!

The cooler you can keep it the higher the overclock you'll get, simple as that.
a b à CPUs
a b K Overclocking
April 9, 2011 3:51:45 PM

I would also get some good Thermal paste with it. The paste can make a huge difference of 5-10C or more if you have bad paste(like the stock paste). Arctic Silver 5 sucks now compared to many other pastes. I just need to find the graph that was on one of these threads awhile ago.
a c 96 à CPUs
a c 228 K Overclocking
April 9, 2011 5:26:21 PM

Haserath said:
I would also get some good Thermal paste with it. The paste can make a huge difference of 5-10C or more if you have bad paste(like the stock paste). Arctic Silver 5 sucks now compared to many other pastes. I just need to find the graph that was on one of these threads awhile ago.


AS5s cure time is a big negative against it, I'm presently using ICD24, but was looking to see what may be better that's available today, have you got any recommendations?
a c 227 à CPUs
a c 105 K Overclocking
April 9, 2011 5:45:19 PM

4Ryan6 said:
AS5s cure time is a big negative against it, I'm presently using ICD24, but was looking to see what may be better that's available today, have you got any recommendations?



I use IC Diamond 24 myself but have also heard good things about Shin Etsu and MX -4.
a b à CPUs
a b K Overclocking
April 9, 2011 10:15:09 PM

I think IC Diamond is one of the better thermal compounds out. It would be hard to beat unless you get something like liquid metal.

I would recommend TX3, MX-4, Shin estu G751, or IC Diamond as the better compounds.

The best part of IC Diamond is that it's not thermally conductive, so you don't have to worry about it affecting components.
a c 96 à CPUs
a c 228 K Overclocking
April 9, 2011 10:47:41 PM

Thanks Guys!
April 11, 2011 11:13:41 AM

I bought a CoolerMaster v6 gt.
I want to do some benchmarks before and after overclocking to see the difference.

Can you guys tell me some benchmark programs for cpu that just doesn't take long time.
Does overclocking the cpu also affect game performences ? should i do some benchmarks with fraps too ?
a b à CPUs
a b K Overclocking
April 11, 2011 8:19:01 PM

Overclocking the CPU only makes a big difference in CPU bottlenecked games, which are rare(as long as you have a decent monitor >=1080p). Or if you have a high end SLI/CFX setup. It will produce a few extra frames though, but it's not noticeable.

Sisoft Sandra tells the theoretical best of your CPU. It doesn't exactly translate into real performance numbers, but it's at least something to try.

You could set it up and fold for our team...*hint, hint* ;)  and check your PPD numbers.

3D mark 11 has a CPU test and does game testing, so you can get both in at once.
April 11, 2011 8:34:30 PM

I have finally overclocked my i5 2500k @4.5ghz - 1.28v MaxTemp 69C

You are right it doesn't make any big difference in games. I checked Crysis2 and Homefront. Just 1-2 fps gain.

I tried overclocking to 4.8ghz but it seems the temps are not safe. 4.8ghz - 1.35v and the temps avg is 70C and the max is 73C.
a b à CPUs
a b K Overclocking
April 11, 2011 8:46:26 PM

xperator said:
I have finally overclocked my i5 2500k @4.5ghz - 1.28v MaxTemp 69C

You are right it doesn't make any big difference in games. I checked Crysis2 and Homefront. Just 1-2 fps gain.

I tried overclocking to 4.8ghz but it seems the temps are not safe. 4.8ghz - 1.35v and the temps avg is 70C and the max is 73C.

That's actually a decent temp. Since this isn't my hardware, I'm not going to recommend going above that temp. But that is about the recommended safe temp to stay under, to be safe you could try keeping it@4.8 with it's lowest stable voltage which should lower temps a bit unless you got lucky and that is the actual lowest voltage to run @4.8.

What are you using to stress the CPU? Prime 95, Intel Burn Test, and OCCT are good stress test programs to use when trying to find lowest stable voltage, and the max temp of the cores.
April 11, 2011 9:13:48 PM

You are saying that getting temps around 70-73C is safe ( on the edge maybe ) ?

I just use Prime95. I didn't let it finish, I just left it for about 30 min. I am using it's default preset. the other one that says 'maximum heat' seems to be dangerious.

The default preset is already getting most of the cpu, I think the 2 other one is for killing cpu.

BTW,Is that possible that a program or maybe a game make 100% cpu load ? When I watch taskmanager on windows, the cpu activity is very low. I never have seen the cpu goes more than 70% usage. Actually it's always below 30%
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a b K Overclocking
April 11, 2011 9:32:32 PM

I don't know of any program that can actually use every part of the CPU at once. That's why I like to stress test with multiple programs; they all test different parts of the CPU. Prime 95 mostly does integer(maybe even all), so the FPU might be unstable even if Prime 95 passes.

Stress tests are much more more strenuous than any program as well. The parts that the tests use will be stress to their max, some stress tests could just load a bunch of 1's into the processor just to make it @ 100% use.

No actual useful program will ever be able to fully load a CPU. Windows will interpret a load in task manager as 100%, but that's not entirely true. Prime 95 should show 100% in task manager if you have it setup correctly.

Your cpu is so fast for today's programs that it won't be used@100% for awhile unless you do something very paralleled like Folding@Home(I don't know of anything else that can make my 920@3.8 hit 100%).
April 12, 2011 8:02:16 AM

I tried running Prime95 for 3 hours @ 4.8ghz - 1.35v but unfortunately there was an error on core #3 and the max temp went upto 79C.
I think I should give up on 4.8ghz for now. Increasing cpu voltage more than 1.35v it will be more hotter than before.

I have also tried 4.7ghz on 1.33v still no luck on this one too. temps are high as 70C and it's also unstable.

I wish I had bought a better cpu cooler.

Edit: I have a critical question : I was running tests for stability for 4.5ghz and after prime95 and occt finished, suddenly occt shows number 4000mhz as cpu clock! then I checked the cpu-z it was the same. Wth ?? How does this happens ? I set multipier to 45 in BIOS why in windows it shows 4000mhz ?
a b à CPUs
a b K Overclocking
April 12, 2011 8:04:42 PM

Does it show 4ghz when you put a full load on it?

If so, I would first check the windows power settings and see if the max frequency % somehow got changed. If it still is at 100% then I would clear the bios and just set up the overclock again.

Not exactly sure what could've caused this.
April 12, 2011 8:16:33 PM

Actually it only happened 2 times since I started changing bios settings for first time.
I am not sure if Turbo Boost is intefering or not. Because before that I was testing turbo boost at 4ghz to see how it works.
I had it disabled after that for manual oc.

This is really a weird thing! The multiplier is set to 45. How does the cpu runs at 4ghz ?

I also have Enabled 'Real-Time Ratio Change In OS'. Maybe this is cause of changed clock ?
a b à CPUs
a b K Overclocking
April 12, 2011 8:34:32 PM

Oh right, I forgot about turbo boost. :lol: 

Yeah "Real-Time Ratio Change" is turbo boost apparently, so if you disable that then set the clock manually to 45 that should let you keep it at 4.5ghz instead of 4ghz.
April 12, 2011 9:07:39 PM

Ok then I have to disable that one too.

BTW, I am testing the cpu @ 4.7ghz - 1.35v . After running prime95 for 1 hour, the temps are 75C 80C 78C 72C.

I want to know can I keep this oc with those temps ? Or should I go back at 4.5ghz ?

Anyway Thanks for your replies and sorry to bother you. I am really grateful.
a b à CPUs
a b K Overclocking
April 12, 2011 10:42:41 PM

That would be about my limit if I were to use that setup.

The recommended temp would be ~75-78C(Intel gives a Tcase temp of 72.6C which is a few degrees lower than the core temps given in most temp monitoring programs).

If you could use the extra speed then you could keep that, personally, I would keep it at 4.5ghz with a lower voltage, since power usage usually goes up exponentially once the processor is reaching it's limit. This would also ensure that your processor shouldn't be affected from the overclock within it's lifetime. If you get a better cooler, the processor should easily be able to handle a higher clockspeed/voltage.

No problem, it's no trouble at all. ;) 
April 13, 2011 6:22:11 AM

I disabled 'RealTime Change In OS' as you said but when I saved and restarted the pc, in windows it show 4500mhz ! ( multiplier is set to 47 ).
There is something wrong. My suspect is the TurboBoost. I have it disabled. however all core multipliers were set to 45.

I think the mobo reads those TurboBoost core multiplier numbers instead of the CPU Clock Ratio upon system start
a b à CPUs
a b K Overclocking
April 13, 2011 11:23:05 AM

Hmm.. I don't have one to test out myself. That doesn't seem to happen with the older i7 generation.

How about if you disable all the power saving features like C1E, EIST, and C3/C6 states?
April 13, 2011 11:44:47 AM

I did that before. I have disabled them plus CPU thermal monitor.

I decrease vcore by 0.005. it's stable @ 4.7ghz - 1.345v . OCCT's Linpack for 1 hour without any errors. and Prime for about 4hours.
The temps were almost the same as last time.

with 1.34v one worker failed in prime95. so 1.345v should be the lowest for 4.7ghz

Can the temps be lowered by touching other voltage controls in BIOS ? Like Qtt,Dram,cpu pll, etc

a b à CPUs
a b K Overclocking
April 13, 2011 12:11:24 PM

Qtt-Maybe, but it doesn't affect it much(going from 1.2 to 1.35 for me changes the core temps maybe 5-10C, but that is a significant change in voltage).

Dram- Not at all, that is the Ram voltage

Cpu Pll- This will affect the voltage that sends the clock signal to the CPU, not exactly sure if this affects temperature much, but it seems like it might. If you lower it too much the CPU might not receive the clock signal, but I've also heard that lowering/raising this will help the CPU clock better with lower voltage due to noise. The vcore might not be able to be lowered if the transistors actually need that voltage to physically switch though.

Most of the other voltages are for northbridge/southbridge, so I would just leave those alone.

The core voltage is the only voltage that will really affect the core temps. You might just have to back off the overclock to keep get a decent temperature.
April 13, 2011 5:26:06 PM

ok then i will stick to lower clocks.

a problem appeared when I wanted to get 4.6ghz stable voltage. prime95 was running and when I went for dinner the pc was restarted.
I checked bsod dump files and there was nothing. I have also checked Prime95's results.txt and there was no error or anything.
I have checked the eventviewer also there was nothing just an unexpected system restart.

I disabled automatic system restart on failure right now and running tests again.

BTW, what could cause this ?
a b à CPUs
a b K Overclocking
April 13, 2011 7:30:25 PM

There probably wasn't enough Vcore voltage so the comp just crashed when you put a load onto it. I've had that happen to mine when I was trying to hit 4.0ghz, and it skewed the image then restarted itself after a few seconds. Prime 95 didn't even have time to give errors. There wasn't even a BSOD. Still runs happily at 3.8, so it shouldn't be harmful; mine just can't hit 4ghz.
April 13, 2011 7:46:40 PM

Do I have to increase the vcore ?

I have tested using Occt's linpack (1hour) there was no error. Also played a game.

But there was something weird. When I was installing the game. Just right after the installation finished, when I pressed 'Finish' a blue screen suddenly showed for 0.5 sec. In that moment there wasn't any message written on it. everything was normal after that.

I want to keep 4.6ghz on lowest voltage possible to avoid unnecessary high temps. 4.5ghz max temps on full load was 69C and 4.6ghz max temp is 71C.
It is worth to keep the extra clock.
a b à CPUs
a b K Overclocking
April 13, 2011 8:07:02 PM

That .5 second blue screen sounds more like a software 'glitch'. I haven't heard of anything like that being caused from stability issues.

I've heard of many people doing a run of Prime 95 over the night(8 hours) to make sure it's stable, because just one little fluctuation of voltage that the processor recieves can make it crash.
April 13, 2011 8:19:53 PM

Sure I will leave it over night.

But the 'Blend' test takes about 3-4 hours. not 8 hours.
Which setting will take 8 hours ?

a b à CPUs
a b K Overclocking
April 13, 2011 8:43:28 PM

It should run constantly until you stop it unless you changed the settings to make it only run a certain length of time. Is the CPU setting under Options changed to run for a certain amount of time?
April 14, 2011 11:37:07 AM

After running over night the pc restarted again and no trace of error.
Also the temp hit 74-75C.

I think I will stick to 4.5ghz. I just wasted $70 on a trash cpu cooler.

Thank you for assisting me. I really learned a lot from you.
!