Problem overclocking 4770K on GA-Z87X-UD3H - multiplier goes down under load

[coypuppy]

This is my first post here. I am trying to overclock my Haswell I7-4770K on the GA-Z87X-UD3H board using latest 10b bios. No matter what options I choose I cannot get the multiplier to keep stable under load (prime95). I monitor frequency using CPU-Z. Even if it appears to run at 4.2GHz, as soon as you start prime95, it goes down and the oscillates between 35 multiplier and 39 multiplier. This is regardless of enabling/disabling turbo, manually setting each core's multiplier, disabling thermal throttling and EIST. I've set the CPU core voltage to 1.2V (the "auto" overclock sets it to 1.27 where it was for the last 2 years).

I had this PC for 2 years and had it left on BIOS default 4.2GHz overclock (auto overclock) as I wasn't concerned too much about performance as I was about stability. Now I'd like to tweak it, even if just a bit.

I mean surely it can't be THAT complicated. I am not messing with BCLK and straps and all that jazz. Just a simple multiplier for modest overclock. What am I missing?

 

[MNMadman]

The CPU will throttle automatically to save itself. Seems like that's what is happening here, despite you disabling the options in the BIOS. It has likely been doing this the entire time you've had the PC overclocked.

What are you using for cooling, and what are your temps under load?

Also note that Prime95 loads the CPU way more than anything you will ever do in the real world. Most people consider it overkill for CPU loading.

 

[coypuppy]

The CPU will throttle automatically to save itself. Seems like that's what is happening here, despite you disabling the options in the BIOS. It has likely been doing this the entire time you've had the PC overclocked.

What are you using for cooling, and what are your temps under load?

Also note that Prime95 loads the CPU way more than anything you will ever do in the real world. Most people consider it overkill for CPU loading.

I have BeQuiet! dark rock (or something).

Thermal throttling is what I suspected as well but I thought it would take considerable time (5-10 min) to reach throttling temperatures. But it seems I am pushing this CPU too much - 4.2GHz at 1.2V and as soon as you load it it hits 70C (core temp). If I use AIDA64 the multiplier drops to 39 and stays there indefinitely (with prime95 it jumps 35-39); that's consistent with prime95 being a heavier load, I think. In fact the PC froze 3 times and I had to reboot even with no load.

Loaded defaults, keeping it at 3.9GHz and 1.08V, idle is 29-31C. Loading it with AIDA64, still getting 3.9GHz, V core is 1.12V and around 60C. But temperature jumps a lot (48-62C) and is never the same on all cores so I'm wondering if my heatsink is not correctly installed (unequal core temperatures are usually a sign of improper cooling, no?). As it stays at 3.9GHz, I'm guessing load defaults did not reset the disabling of turbo. Maybe I can try 4.2GHz later but on 1.1V instead of 1.2V?

 

[wingman99]

+1 I would check your CPU temp first keep under 90c. Prime 95 is a good program for testing, also you can look for prime numbers.

 

[coypuppy]

+1 I would check your CPU temp first keep under 90c. Prime 95 is a good program for testing, also you can look for prime numbers.

Looks like you guys are right. I tightened some screws on the heatsink and lowered VCORE and used AIDA instead of Prime95 and now multiplier stays 42 all the time. Even with prime95 it seems to stay at 42 through temperature is much higher, over 90C versus below 70C with AIDA. Thanks for your suggestions.

 

[wingman99]

Glad you have it fixed, I would also check your fan speed.

 

[MNMadman]

Yeah, with the temps anywhere near 90°C, I wouldn't recommend using Prime95 for CPU loading. AIDA is a much more realistic program for CPU loading. With gaming loads, air-cooled CPUs should be 60°C or less with a better-than-stock cooler.