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Help me OC'ing i5-2500k to get it stable

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New Member
Aug 25, 2016

i5-2500k + SPC Fera3, AsRock P67 Pro B3, Corsair Vengeance 4G 1600Mhz, Sapphire HD7850 1GDDR5 256bit, Zalman Z11+, AeroCool Strike-X 500w

Temperatures are fine. At 4.5Ghz no more than 67*C in IBTv2/OCCT with full stress enabled. Case is quite tidy, IMO airflow is good. 2x Zalman's 120mm in take at front (1 under 5.25' bay, second at 5.25' bay) + 1x Zalman's 120mm out take + 1x SPC Sigma Pro 120mm outtake at top. My hand feels cold when i put it inside.

My point is to get stable 4.5Ghz at my i5-2500k getting the lowest voltages. Now my computer shows up bluescreen, or just crashes (crashed video and sound - restart needed).

My UEFI settings:

After getting crashes i changed:
vCORE: offset lvl 2 -0.080v > offset lvl2 -0.075v
Internal PLL Overvoltage: Enabled > Disabled
CPU PLL Voltage: 1.668v > 1.627v (1 step lower if i remember)
BLCK: 100.1Mhz > 100Mhz (wanted to get rock-solid 100Mhz, not 99Mhz-100Mhz, but i decided not to touch it) - some more comment below
Long/Short PDL: 180/220 > 250/250

Comment about BLCK: Before i5-2500k i had i3-2120, when I tried to OC i3 by it's BLCK to 103Mhz i was getting same problem, crashes after some time of gameplay/internet/music, sharp horizontal stripes colored depending on background.

Now, when I was writting this i got bluescreen, so I changed:
CPU PLL Voltage: 1.627v > 1.668v

Through ITBv2/OCCT PC goes perfectly, but after playing LoL/surfing internet+music etc. I was getting crash with stripes.
Drivers are up to date, updated with DriverBooster. I'm sure it's not graphics card bad, i haven't touched it, also before setting lower voltages everything was fine at 4.5Ghz, offset lvl2/3 -0.035v and some lower like -0.050v.
My aim is to get the lowest voltages, so also temperatures.

I got fans set at the lowest speed, and CPU's temperature aim set at 50*C, so fans are speeding up after reaching this temperature on CPU.
In idle i get 30-40*C with fans moving at ~400/500RPM.
In highest stress (ITBv2 maximum settings at 4 cores + browser with music and this site open) I got -/+65*C as I said (SigmaPro3 is easy to be heard, but in general PC is quite silent even in stress: fans at 1400-1700rpm).
In games it doesn't even reach 55*C.
Now PC goes through 15runs at IBTv2 max stress.

I would like you to get a look at this guys if there is any option to get my aim, thanks for every help.

ITBv2 just finished it's work. It said no problems detected.
HW Monitor says that, min vCORE was 0.920v, and max vCore was 1.328v.
I saw one i5-2500k AsRock ProB3 OC'ing post in internet, and some guy with -0.075 offset settings had max ~1.295v on Core.
Is it normal, that it's different at same CPU/MoBo? Well, heh had offset level 4, but it doesn't change maximum vCore, or does?
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I would set everything back to default and only increase vcore for a overclock only to 4.5GHz. The total voltage calculation in CPU-Z is what you have.
Agree with Wingman99 on this.
Its not a picky CPU by any means but reset to defaults up the CPU voltage til stable and leave the rest on auto. Then start fine tuning if you wish for the remainder of the settings after its stable.

PS good CPU :) Mines played nicely over the years, but starting to feel a little long in the tooth with board features compared to newer systems.
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