Question Single core overclock i7-7700k

[parmi93]

I am trying to overclock my i7-7700k.

System specs:

• CPU: i7-7700k @ 4.20 GHz (Turbo boost: 4.5GHz) [delidded]
• Mobo: Asus Maximus IX Extreme
• GPU: Gigabyte - GTX 1080 Ti Waterforce WB Xtreme Edition 11G
• RAM: 32GB - G.Skill - Trident Z RGB - DDR4 3600Mhz - 32GB (8GBx4) - 16-16-16-36
• PSU: Seasonic - PRIME 850 W Titanium
• Custom Cooling system:
  • Radiator: x2 radiator (520x30x60mm)
  • Radiator FAN: x8 Noctua (120x120x15mm)
  • Pump: EK-XRES 140 Revo D5

At the moment these appear to be the two stable configurations:

4.9GHz Config

• CPU ratio: x49
• Vcore in BIOS: 1.375 V
• Vcore mode: manual
• XMP profile: enable (DDR4 - 3600MHz)
• CPU integrated GPU (iGPU): Enabled
• LLC: 5
• AVX offset: x0
• Windows 10 power management: High performance
• Vcore idle (HWiNFO64): 1.376 V
• Vcore Stress (HWiNFO64): 1.366 V
• Vcore idle (measured*): 1.384 V
• Vcore stress (measured*): 1.371 V
• OCCT stress temperature (AVX2): 74 °C

5.0GHz Config

• CPU ratio: x50
• Vcore in BIOS: 1.405 V
• Vcore mode: manual
• XMP profile: disabled
• Integrated GPU (iGPU): disabled
• LLC: 5
• AVX offset: x0
• Windows 10 power management: High performance
• Vcore idle (HWiNFO64): 1.408 V
• Vcore Stress (HWiNFO64): 1.398 V
• Vcore idle (measured*): 1.414 V
• Vcore stress (measured*): 1.402 V
• OCCT stress temperature (AVX2): 66 °C

*FLUKE 179 multimeter using the average function and measuring for 1 minute

With the 5GHz configuration if I enable the XMP profile or the iGPU I do not pass the OCCT test or the system crashes with a blue screen, at 5.1GHz the CPU is always unstable (regardless of XMP profile or iGPU).

Now I'm trying to set a different ratio for each core, in particular I'm trying this configuration:

• CPU core 0 ratio: x51
• CPU core 1 ratio: x50
• CPU core 2 ratio: x50
• CPU core 3 ratio: x50
• Vcore in BIOS: 1.405 V
• Vcore mode: manual
• XMP profile: disabled
• CPU integrated GPU (iGPU): disabled
• LLC: 5
• AVX offset: x0
• Windows 10 power management: High performance

With this configuration I passed a one hour OCCT (AVX2) test without any problems, but I noticed something odd with the clock reported by HWiNFO64.
When the system is in idle I have noticed that the core clocks keep jumping between 5.0GHz and 5.1GHz, sometimes all are at 5.1GHz, other times all are at 5.0GHz, and some time some are at 5.0GHz and others at 5.1GHz.

Then when I started a stress test (OCCT - AVX2) all cores were always at 5.0GHz, they didn't touch 5.1GHz even for a moment.
Can anyone explain to me what is happening?
I would have expected core 0 to be fixed at 5.1GHz and all others at 5.0GHz, why the clocks keep jumping between 5.0GHz and 5.1GHz?

Any suggestions are appreciated, thanks.

 

[Karadjgne]

LLC 5 is for LN2 oc's, not standard mechanical cooling, use 3 or 4 instead as you are dropping vcore too low to offset the amount of LLC voltage applied, which makes it unstable.

Vcore isn't the only voltage to be concerned about, you also will need to adjust VCCSA, VCCIO, Ring voltages and especially VID, which should be no less than 0.05v above or below vcore, depending on the offset polarity.

And that's not including the changes to the Amperage, long/short duration should be 130%, disable phase limiters, disable c-states etc.

Vcore is what the cpu demands, and you've got it set at 1.4v ish. VID is what the VRM's are supplying, and thats 1.225v before LLC. Your demand is higher than your supply = limited core speeds.

You want advice? Go research about OC 7th Gen cpus. Rog forums is a good place for that. Overclockers.com, there's multiple sites with writeups on what works, what doesn't do anything, what to avoid etc. You need to know what all of the settings in your bios actually do, what they affect, what affect adjustments have, what relationships changing those settings affect. There's a Lot more to OC than just maxing LLC and minimizing vcore and you'll need to know a bunch of it in order to get a really good and stable OC with voltages you can live with and temps you approve of.

 

[parmi93]

First of all thanks for your answer, @Karadjgne

I've been reading everything I find about overclocking for weeks.

LLC 5 is for LN2 oc's, not standard mechanical cooling, use 3 or 4 instead as you are dropping vcore too low to offset the amount of LLC voltage applied, which makes it unstable.

This is the first time I've heard that LLC5 is for LN2, are you sure?
If you look at my previous post you will notice that with the LLC5 I have a drop of 3-4 mV (under load) compared to the Vcore set in the BIOS.

Vcore is what the cpu demands, and you've got it set at 1.4v ish. VID is what the VRM's are supplying, and thats 1.225v before LLC. Your demand is higher than your supply = limited core speeds.

As far as I know, Vcore is what VRM's are supplying to the CPU (measured with the multimeter) and VID is what the CPU demands, do not look at the VID in the screenshot, it is always fixed at 1.225v, this is due to the fact that I have set the Vcore in manual mode (override) which deactivates the VID.


I am currently experimenting with the VCCSA and VCCIO to see if I can stabilize the system

 

[Phaaze88]

LLC 5 is for LN2 oc's...

Are you sure about that? Asus does Level 1-7, or 1-8 on their boards. You have an Asus board; their bios layout has been pretty consistent.
Asrock on the other hand, has 5 levels to the LLC on their boards, so 5 would be extreme there.

 

[Karadjgne]

Are you sure about that? Asus does Level 1-7, or 1-8 on their boards. You have an Asus board; their bios layout has been pretty consistent.
Asrock on the other hand, has 5 levels to the LLC on their boards, so 5 would be extreme there.

Bios differs. My Asus board does 1-5 with 5 being high. I've had ASR that did 1-5 with 1 being highest. My old msi board did %'s not a menu.

Either way, for high OC, you'd be looking at the 50-66% added, not 100% option. So if Op's bios is 1-7 with 7 high, then 5 is ok, but if the option is 1-5 then 3/4 would be advised.

But yes, because of the amount of LLC added at the highest setting, it should only ever be used with chemical cooling, not mechanical cooling, as in phase change or peltier or LN2 or other cooling types that can reduce temps Below ambient.

 

[Phaaze88]

Well, crapbaskets. Mines 1-8 with 8 being high.

 

[Karadjgne]

As far as I know, Vcore is what VRM's are supplying to the CPU (measured with the multimeter) and VID is what the CPU demands,

VID is the Voltage Identifier. It's what the VRM's supply to the cpu. Vcore is what the cpu demands. SVI2 is what the cpu actually uses. LLC is a line level calibration, it's a pre-emptive voltage applied before each ripple (vdroop) and does only 1 thing, Adds voltage. Not only to the droop so that SVI2 doesn't exceed vcore but also to peak voltage. So you set a vcore of 1.23v but the cpu actually gets 1.43v (at high level). If VID is set too low and there's not a positive offset, pc crashes, blue screens, gets funky whea errors etc.

So it all has to balance out where supply is only slightly more than the highest demand, which happens at idle.

VCCSA is system agent, and helps with stability of pcie bus, L3 cache and other things. VCCIO is the integrated memory controller. When you OC the cpu that's only half of it, you also may need to add additional voltage to the stuff that supports the cpu too. Think of it like putting a 500hp engine upgrade in grandma's old cruiser, but leaving the stock skinny tires on, you step on the gas and do nothing but spin tires.

 

[parmi93]

VID is the Voltage Identifier. It's what the VRM's supply to the cpu. Vcore is what the cpu demands.

@Phaaze88 could you confirm that?
I always read the opposite, VID is the voltage the CPU asks from the motherboard, and Vcore is what the CPU receives

 

[Phaaze88]

I'm on X299, which functions a little differently.