Prime95 help

sreeve1993 · 14 Jun 2015 at 17:42

Hello guys

I've recently overclocked my i5 2500K CPU to 4.2ghz (my first time haha). After running a test with Prime95 I noticed something strange and I'm not sure its normal.

Anyway after 30mins of testing, the temperature seems fine and maximum temp is 70c and at idle its avg of 35-40c. No errors are found. However, when using CPUID HWMonitor it shows that when Prime95 is undergo the CPU core is only hitting at 3.8ghz and not the full 4.2ghz. But when I stop the test my CPU seems to switch between these speeds 1.6ghz-4.2ghz.
Is prime95 meant to do this?

To note, when I overclocked I did not change many settings from stock. The only setting I have changed is that:

Spread Spectrum is : off.
Advanced Turbo 50: off
Interal PLL Overvoltage: off

Everything is stock/auto. I know that I need to change some setting but right now I'm not so confident.

Here are my specifications aswell

- Antec 300 case - (no front panel fans)
- MSI HD 6850 Cyclone Power Edition 1024MB GDDR5 PCI-Express Graphics Card
- Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor
- Corsair XMS3 16GB (4x4GB) DDR3 PC3-12800C9 1600MHz Quad Channel Kit
- Gelid Tranquillo CPU Cooler (Socket 754/939/940/AM2/AM2+/AM3/LGA775/LGA1155/LGA1156/LGA1366).
- ASRock Z68 Extreme4 Gen3 Intel Z68 (Socket 1155)
- XFX 750w PSU
- Samsung SpinPoint F3 1TB SATA-II 32MB Cache - OEM (HD103SJ / ST1000DM005)

Any help will be appreciated

Stefan

wazza300 · 14 Jun 2015 at 17:44

download cpu-z and look in that when stressing with prime95

if it goes to 4.2ghz in cpu-z then ignore hwmonitor

if it doesn't try enabling advanced turbo and set it to 42x

sreeve1993 · 14 Jun 2015 at 17:46

I already have it and never seemed to think of looking into it haha. Well test it right now and see what happens

sreeve1993 · 14 Jun 2015 at 17:51

CPU-Z shows the same, it switches between 3.6-3.8ghz. For the multiplier it shows x37 (16-60). The moment I turn prime95 off is when it goes back to x42 multiplier.

wazza300 · 14 Jun 2015 at 17:52

not sure with asrock boards but have you set the multiplier to 42x?

that's all you should have to do,if it still wont boost to 4.2ghz enable each turbo ratio to 42x aswell

sreeve1993 · 14 Jun 2015 at 17:58

Yeah I set it to 42x in the BIOS. The feature Advanced turbo 50, shall I try changing that to 4.2ghz? At the moment it is disabled.

When I do click on it, it does give a list of speed ranging between 3.3ghz-5.0ghz.

wazza300 · 14 Jun 2015 at 18:00

yh try enabling it and setting it to 4.2ghz

sreeve1993 · 14 Jun 2015 at 18:00

Okay thanks, will give it a go and let you know

sreeve1993 · 14 Jun 2015 at 18:10

Just tried it, if I enable it, all CPU settings disappear, and If I disable they appear again.
There is a setting 'Load Optimized CPU OC setting' and this setting is which has the list of speeds between 4.0-5.0ghz but next to each number it shows 'turbo'?

If nothing, I will take a picture of all my settings and type them all in here as I'm not sure how to upload an image.

wazza300 · 14 Jun 2015 at 18:15

do you have a normal turbo? it might say turbo ratio,and it lets you set 42 for each of the four cores

that and a 42x cpu multi should give you 4.2ghz

sreeve1993 · 14 Jun 2015 at 18:24

Yes, the setting is called CPU Ratio setting, and I set this too 42.

After reading some info about my motherboard settings, I may have found the problem.

Turbo Boost Power Limit This is the maximum power that can be drawn when turbo is enabled. If set too low, CPU may throttle when this limit is reached.

Core Current Limit This is the same as above, but is current, instead of wattage. Volts x Amps = watts, turbo mode allow you to set current and wattage limits, as well as voltage.

These settings for me are on auto, and what I remember is that Turbo Boost power limit short and long duration power limits are low figures (will get the exact settings)
And my core limit is 150. My CPU load-line calibration is level 5 (1-5).

EDIT:

Got the exact values now
Turbo boost power limit (short duration 118) (Long duration 95) (Long duration maintained 1 second)
Core current limit 150.

sreeve1993 · 14 Jun 2015 at 19:50

I have found the problem. The turbo power limits were too low which is why my CPU was throttling. I have now set short duration to 300 and long duration 300. Core limit 300. When running prime95 it uses the full 4.2ghz. Temps have increased to 75c but I think this is because voltage is set on AUTO.

Cpu-z shows its 1.272.