: Single core overclock i7-7700k
: Single core overclock i7-7700k
I'm attempting to push my i7-7700k overclock.
System details:
CPU: i7-7700k @ 4.20 GHz (Turbo boost: 4.5GHz) [delidded]
Motherboard: 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
Power supply: Seasonic - PRIME 850 W Titanium
Custom cooling setup:
Radiator: two units (520x30x60mm)
Radiator fans: eight (120x120x15mm)
Pump: EK-XRES 140 Revo D5
Currently these seem to be the two stable setups:
4.9GHz configuration
CPU ratio: x49
Vcore in BIOS: 1.375 V
Vcore mode: manual
XMP profile: enabled (DDR4 - 3600MHz)
CPU integrated GPU (iGPU): active
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 configuration
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
*Using Fluke 179 multimeter with average mode for 1 minute
With the 5GHz setup, if I turn on XMP or enable the iGPU, the OCCT fails or the system crashes with a blue screen. At 5.1GHz it remains unstable (no matter the settings).
I'm attempting to adjust the ratio per core—specifically:
CPU core 0: x51
CPU core 1: x50
CPU core 2: x50
CPU core 3: 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
With this setup, the OCCT test over one hour passed without issues, but I observed irregular clock readings in idle mode—core speeds fluctuating between 5.0GHz and 5.1GHz, sometimes all at 5.1GHz, other times all at 5.0GHz, and occasionally a mix.
During an OCCT stress test (AVX2), all cores consistently stayed at 5.0GHz, never reaching 5.1GHz.
Can anyone clarify what's happening?
I expected core 0 to stabilize at 5.1GHz while others remained at 5.0GHz; why do the clocks keep jumping like this?
Any advice would be greatly appreciated. Thanks.
LLC 5 is intended for LN2 cooling systems, not typical mechanical cooling methods. Adjustments should focus on 3 or 4 instead, since lowering the vcore too much reduces its effectiveness against the applied LLC voltage, causing instability. Vcore isn't the sole factor—VCCSA, VCCIO, ring voltages, and especially VID must be set within 0.05v above or below the vcore, depending on polarity offset. This isn't just about changing the amperage; long or short durations should be around 130%, phase limiters should be disabled, c-states turned off, etc. The vcore reflects the CPU's needs, and setting it to around 1.4v is reasonable. VID comes from the VRM and is currently at 1.225v before the LLC stage. If your demand exceeds your supply, core speeds will be limited. For guidance, research OC settings for 7th Gen CPUs—forums like Rog forums, Overclockers.com, and other communities offer valuable insights on what works, what doesn't, and how to avoid issues. Understanding all bios settings and their impacts is crucial for achieving stable overclocking with acceptable temperatures.
Initially, thank you for your response.
@Karadjgne I've been studying overclocking techniques for several weeks.
This is the first time I've come across information suggesting LLC5 is intended for LN2 cooling. Are you certain about that?
In my earlier post, you can see that with the LLC5 setup, I experience a 3-4 mV drop under load compared to the Vcore set in the BIOS.
To be clear, Vcore represents the voltage supplied by the VRM to the CPU (measured with a multimeter), while VID is the voltage the CPU requests. The VID remains constant at 1.225V because I've configured Vcore in manual override mode, which disables VID.
I'm currently testing VCCSA and VCCIO to determine if they help stabilize the system.
Are you certain about that? Asus includes Levels 1 through 7, or even up to 8, in their board designs. You own an Asus board; its BIOS layout remains fairly uniform. Asrock, however, features five levels to the LLC on their boards, which would be quite unusual.
Bios varies. My Asus board operates 1-5, where 5 indicates high. I've experienced ASR models that functioned 1-5 with 1 representing the highest setting. My previous MSI board didn't have a menu for %'s. For maximum performance, you'd aim for 50-66% added, not 100%. So if Op's bios ranges from 1-7 and 7 is high, 5 is acceptable; however, with a 1-5 range, 3 or 4 would be better. But due to the significant LLC boost at the top setting, it should only be used with chemical cooling methods, not mechanical ones like phase change, Peltier, LN2, or other systems that can lower temperatures below ambient.
VID stands for Voltage Identifier, representing the voltage provided by the VRM to the CPU. Vcore is the voltage the CPU requires. SVI2 reflects the actual voltage used by the CPU. LLC performs line-level calibration, applying a preemptive voltage before each ripple (VDROOP) to simply add voltage. It ensures both droop limits and peak voltage are respected. For example, setting a vcore of 1.23V may result in the CPU receiving 1.43V under high load conditions. If VID is too low without a positive offset, the system may crash or display blue screens and other abnormal behaviors.
Balance is essential, with supply only slightly exceeding the highest demand, especially during idle states. VCCSA supports stability for the PCIe bus, L3 cache, and related components. VCCIO acts as the integrated memory controller. When overclocking the CPU to its maximum, you might need extra voltage for supporting elements too—similar to installing a powerful engine in an old car while keeping the original tires, causing the wheels to spin without improvement.