Seeing CPU clock jitter with PLL Overvoltage off

[ArrowMk84]

I turned off PPL Overvoltage to get sleep to work right, and now I'm seeing up to half a megahertz of clock jitter in both the CPU and DRAM clocks (where before it was a tenth of a megahertz). I've been running Prime95 large FFT test for over half an hour now (just made the change), and I haven't seen any problems yet (I'm about to do the blend test next), but should I be concerned? Or is it normal to see this much jitter?

I've got my CPU set to 4.6 GHz, using a multiplier of 46 and a BCLK of 100. Vcore is at 1.35 (with a max temp of 79C on one of the cores when doing Small FFTs or the Intel Burn test - so I'm very happy with the overclock). DRAM is set the stock speeds of 1866 MHz, 9-10-9-27-2T. Turbo boost and speed step are off (although, speed step still acts like it's on - weird, but it saves power when idle without hurting performance). Everything else is left on auto.

Thanks!

Edit: By the way, I used CPU-Z and ASUS AI Suite II to monitor the clock frequencies, so yeah, there is some eye-balling involved.

 

[unclewebb]

Most PLLs are extremely consistent and the wander observed is mostly monitoring error.

Try running ThrottleStop. Every time you click on the BCLK button, ThrottleStop will accurately recalculate your base clock speed and the amount of wander will likely be next to nothing.

ThrottleStop 3.00
http://www.techinferno.com/downloads/?did=1

The default multiplier for a Core i7-2600K is 34. Anytime the multiplier goes higher than 34, no matter how it got there, it is using Intel Turbo Boost. Some bios options can be misleading.

The Control Panel - Power Options - Minimum processor state controls your idle multiplier as well as the C1E sleep state.

 

[ArrowMk84]

Thanks. ThrottleStop shows 1 to 2 kHz of jitter, so you're right about it being a measurement error.