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I5 2500k bad core what to do

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March 4, 2013 8:56:08 PM

I have a new i5 2500k cpu, when I try to overclock it and run Prime 95 one of the cores drops to 6% load while all the other cores are at 100%. It starts when I get to 4.1 ghz at 4.0 ghz all cores are at 100%, at 4.1 ghz the one core drops to 6% load.
I would like to overclock it to 4.5 ghz, since its new I don't think they'll warranty it because runs fine at the stock setting, is there another way to have this cpu replaced?

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a c 850 à CPUs
a c 152 K Overclocking
March 4, 2013 9:15:49 PM

No other way but you can try contacting them, does not hurt.
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a b à CPUs
March 4, 2013 9:20:09 PM

If you monitor temps on the individual cores, does that one overheat?
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a c 141 à CPUs
a b K Overclocking
March 4, 2013 10:13:33 PM

What cpu cooler are you using?
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a b à CPUs
a b K Overclocking
March 4, 2013 10:21:57 PM

WTF!Something not right as popatim asked

What cpu cooler are you using?
Are you overclocking correctly ?Basically do it like this might be a little different.First off Download CPU-Z - Realtemp -Prime95 - just like any overclocking you will need to enter the bios. Depending on your motherboard I always recommend going to the Save/Exit section and select restore to Defaults just in case some settings were changed if you were adjusting things so we can start fresh.






Main BIOS Screen:


Save/Exit


One thing that I always recommend is disabling all the things you are not using such as eSata, USB 3.0 etc. After that depending on your motherboard you should have an Overclocking section so we need to go here next.


First go ahead and set your CPU Multiplier between 40 and 45. Since the Baseclock on most P67 motherboards should be 100mhz, 100mhz x 40=4ghz etc. This is the option that we will use because Sandy Bridge is very testy when it comes to adjusting the Baseclock.


Next go to VDroop and change this to without Vdroop. This will basically help reduce sagging while we run Prime95 or Linx and keep the voltage stable.


Next go to Internal PLL Voltage Override and set this to Enable- This is a very important step whenever you are using a multiplier of 40 and greater.


Next go to CPU VCore and set this to manual and then I would recommend starting at 1.300V for 4ghz and if you want 4.5 you will more than likely need about 1.325 but always remember to test in small increments in order to achieve a nice stable overclock. This may vary on your CPU whether or not you have the same identical one as someone else.


Next head over to the memory section of your BIOS and set the DIMM voltage to whatever the manufacturers specifications.


Now we need to configure some other very important features in our Bios which some are completely optional but I would highly recommend changing them for stability.


First go to EIST (Intel Speedstep Technology)and disable this feature. Basically this allows your CPU to throttle down below even the stock 3.4ghz when tasks are at a minimum so it is optional but I always disable it.


Next got to C1E Support and disable this feature. This is another power saving feature but enabling this might cause instability.


Next go to CPU C3 Support and set this to disable. I believe this is also called Sleep where the processor does not need to keep its cache coherent but maintains another state.


Next make sure you have Turbo Mode enabled. Most P67 -Z68 motherboards have this feature.



Next up, memory settings! Make sure to configure this per your memory specifications, or use the XMP function to use the built in SPD settings (if applicable)


Now you can go ahead and Save/Exit to Windows. I would definitely recommend having some Temperature software previsously installed on your system. I swear by Coretemp but there are many others out there. Make sure you keep a close eye on your temps after booting into windows.


Now that you are in windows check you clock settings with CPUZ and I recommend running a stability test such as Prime95. Another great one is LinX which is very intense. You can run it as long as you want and there are many different opinions as to how long you should run the tests to do some research online and make your decision.I usually run LinuX for two hours and then i run prime 95 for twelve hours so far those are what work best for me they might not for you.


That is basically it.
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a b à CPUs
a b K Overclocking
March 4, 2013 10:43:41 PM

First, you don't need 4.5ghz, that's overkill for a system with only 1 GPU, from 3.8ghz to 4.2ghz is great for a 2500k.

Please list your full system specifications too: motherboard, power supply, ram.

Okay so, if one core is dropping like that it's likely need to either drop clocks because that core is unstable, or increase the voltage slightly.

Reset your bios settings completely and make sure your BCLK in bios\uefi is set to 100 too, and do not use any software overclocking software.

Please post your prime95 temperatures, and idle temperatures too.
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March 5, 2013 2:54:03 AM

I should have included more details about my build
its a i5 2500k with a Asrock z77 extreme 4 mobo.
I have a cooler master 212 evo cooler
p1600 ripjaws 16 gb of ram
and run a asus gtx 670 gpu
my psu is a corsair 750hx

I found the problem prime 95 got a error on one of the cores while testing and shut down testing of that core, thats why the load dropped. I have playing with the voltages if I increase the voltage that core doesn't drop out. I found a sweet spot I like its 4.3 ghz The cpu voltage is at 1.185 my temps are 60, 64,66 and 61. It ran stable for 20 minutes.
How do these temps compare to my 4.3 ghz. Also what is VID its at 1.406 volts
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a b à CPUs
a b K Overclocking
March 5, 2013 4:20:29 AM

Fantastic, you should run it for 12 hours straight to make sure it's fully stable, as long as you can. The temperatures seem a tiny bit high, but fine.

I don't think you got a very good chip for overclocking though. It was just a voltage issue for that core. Don't worry about VID, just keep CPU voltage below 1.4v. 1.185 is your CPU core voltage on full load? That's pretty good then.
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