ROG Rampage VI Apex Overclocking Guide

The ASUS ROG team prepared an X299 Kaby Lake-X and Skylake-X Rampage VI Apex overclocking guide for those who wish to get the most out of their Core X-series processors. The guide was originally published by Elmor on the HWBOT forums and is shared at with explicit permission.

Additional BIOS and tools will be available in the HWBOT forum thread.

Guide Version v1.1

Rampage VI Apex Overclocking: Liquid Nitrogen

Kaby Lake-X

Everything is essentially the same as Kaby Lake on Z170/Z270. You can check the Maximus VIII and Maximus IX Apex guides for an update.

Use Slamm’s LN2 profile as a base.

The main difference is that the pin used for DMI voltage is not present anymore, but it’s still mapped to a resistor at the back of the CPU. We’ve solved this by adding a removable pin inside the center of the CPU socket. The pin is included in the motherboard box. It’s suggested to place this pin only on motherboards for LN2 use and tape over the back on Skylake-X CPUs to avoid issues. See Section 8 for installation instructions.

There are four switches available on Rampage VI Apex, which are only usable after LN2 Mode is enabled.

ROG Rampage VI Apex switches

RSVD1 works similar as on M9A, which applies high voltages at startup to ensure you can power on at LN2 temperatures. When the switch is engaged you can’t set lower than the listed voltages, but they can be increased. If you also enable RSVD2, it lets the board know you’re using the DMI pin and will set a more ideal combination of VCCIO and DMI Voltage for lower cold boot and PCI-E cold bug. You should only use RSVD switches on KBL-X.

Voltage RSVD1 RSVD1 + RSVD2
VCCIO 1.45V 1.20V
DMI Voltage N/A 1.60V
PLL Bandwidth Level 8 Level 8
Core PLL 2.25V 2.25V
PLL Termination 1.41V 1.41V



Overall very similar behavior to Broadwell-E: Cold boot around -80 to -90, cold bug about 10*C colder. Some CPUs have IMC cold bug where you get stuck at AE (sometimes 00 after), need to heat up worst case to -50*C to boot.

Load Extreme LN2 profile as a base

To make sure extreme overclocking rules are engaged:

  • Set AI Overclock Tuner to Manual
  • Either Vcore or Vcache 1.41V+

Additionally it’s recommended to use the below settings:

  • SVID = Disabled
  • VCCIO at least 1.35V
  • CPU Current Capability = 240%

Typically you want to be at CPU Input Voltage 2.1-2.3V, CPU Core Voltage 1.45-1.6V, CPU Cache Voltage 1.5V-1.6V. Make sure you’re at least at -30*C before applying these settings.

Cache/Mesh frequency scales with Cache Voltage

When applying CPU Ratio under LN2 scenario, it may take over 10 seconds to actually change. You just need to wait after applying. It’s a bug in Intel µCode.

On 0005 BIOS you might have voltages for Kaby Lake-X showing up in BIOS or TurboV Core, such as Core PLL, Standby Voltage, and PLL Termination. Just ignore; changing them does not affect anything on Skylake-X.


Rampage VI Apex Overclocking: DRAM

DRAM Frequency Expectations

DIMMs per Channel DIMM Rank KBL-X Dram Frequency SKL-X DRAM Frequency
Expected Best Case Expected Best Case
1 DPC Single DDR4-4266 DDR4-4500 DDR4-4000 DDR4-4200
1 DPC Dual DDR4-38666 DDR4-4133 DDR4-4000 DDR4-4133

The values are valid with Samsung B-based DIMMs on ambient cooling and HCI Memtest stable, others might not perform as well. DRAM Ratios are functional up to DDR4-4133 on KBL-X and up to DDR4-4400 on SKL-X.

Kaby Lake-X DRAM overclocking

Same as Skylake/Kaby Lake. You might see slightly higher frequency on this board compared to M9A due to board improvements and higher quality IMCs.


New is working DRAM Ratios up to DDR4-4400.

There’s no major difference between 1T/2T command rate in terms of stability and frequency

You want to be at 4000 CL12 1T for best performance

To maximize frequency you can tune Uncore Voltage Offset (+0.2 to +0.6) and Transmitter DQS Pre-emphasis/De-emphasis (1.400-1.600). If using too much you might get stuck at Windows boot logo or get worse POST issues. Typically your sweet spot voltages will be slightly lower on LN2 compared to ambient.


Rampage VI Apex Overclocking: DMI pin


Rampage VI Apex overclocking DMI pin Rampage VI Apex overclocking DMI pin socket

Insert the pin from the back. Make sure it’s all the way in, maybe need to use more force for the last bit.

Rampage VI Apex DMI pin insert

Use a soldering iron to fix it in place.

Rampage VI Apex DMI pin solder Rampage VI Apex DMI pin soldered
After mounting your Kaby Lake-X CPU you need to measure resistance using the ProbeIt pins to check that it has made good contact. Measurement point is the 4th from the bottom, and it should have less than 2K ohm to GND (most CPUs around 40 ohm).

Rampage VI Apex ProbeIt pins

Switching to Skylake-X

If you are switching over to use a SKL-X, there is no need to remove the pin, simply tape up the back of the CPU as shown below.

Rampage VI Apex DMI Pin Sylake-X

DMI Pin Removal

To remove the pin, you will want to use a soldering iron or hot air gun from below. When the solder starts to melt, push the pin through from the top. The reason for doing this from below is to make sure that the solder does not flood the hole.

Rampage VI Apex DMI pin removal


Rampage VI Apex Connectors

USB BIOS Flashback

USB BIOS Flash Back port is the bottom black port (USB2.0) at the back I/O. Filename should be R6A.CAP.

PCI Express

All PCI Express lanes from CPU and X299 PCH are Gen3.

I/O configuration

Connector Bandwidth Source Note
PCIEX16/X8_1 x16/x8 CPU Always x16 on SKL-X. x8 on KBL-X if PCIEX16_3 is populated.
PCIEX8_2 x8 CPU Only usable on SKL-X 44-lane CPUs.
PCIEX4 x4 X299 PCH
PCIEX16/X8_3 x16/x8 CPU Bandwidth depends on PCIEX8_4 for SKL-X. Max x8 on SKL-X 28-lane CPUs. Always x8 on KBL-X.
PCIEX8_4 x8/x4 CPU Only usable on SKL-X.
CPU_DIMM.2_1 x4 CPU Only usable on SKL-X.
CPU_DIMM.2_2 x4 CPU Only usable on SKL-X 44-lane CPUs. Disabled if PCIEX8_4 is configured in x8 mode.
PCH_DIMM.2_1 x4 X299 PCH
PCH_DIMM.2_2 X4 X299 PCH Supports SATA mode M.2

USB Ports

I/O configuration

Connectors PCB code Color Speed Source Note
Back top 4x Type-A USB3_E1234 Blue USB3.0 X299 PCH Through ASM1074
Back middle 1x Type-A + 1x Type-C USB3.1_EC1


Red USB3.1 Gen2 ASMedia ASM3142 Type-C supports up to 5V 3A
Back bottom 4x Type-A USB1112_U3_56 Black




X299 PCH Bottom black/USB2 port is for USB BIOS Flash Back
Front USB3.0 header USB3_12 Grey USB3.0 X299 PCH
Front USB3.0 header USB3_34 Grey USB3.0 X299 PCH
Front USB3.1 header USB3.1_EC2 Metallic USB3.1 gen2 ASMedia ASM3142 Supports up to 5V 3A
Front USB2.0 header USB1314 Grey USB2.0 X299 PCH
Front USB2.0 header USB10 USB2.0 X299 PCH Shared with ROG_EXT

Installing OS from USB

Windows 8+ installs natively

Windows 7 needs USB drivers slipstreamed. Drives can be moved over directly from Z270.

Windows XP is only supported on KBL-X and only on special XOC BIOS builds. X299 currently has problems with Intel XP AHCI drivers, causing IRQL_NOT_LESS_OR_EQUAL BSOD in some cases. Device ID is identical to Z270. It’s recommended to integrate Asmedia ASM106x AHCI drivers in your XP install and use those ports (bottom dark gray). Make sure to disable the Intel SATA controller from BIOS to avoid the BSOD if using this method. Alternatively you can use a PCI-E SATA card with IDE mode support.

SATA Ports

I/O configuration

Connectors Color Speed Source Note
Top 2x + 2x Light grey SATA3 X299 PCH AHCI Mode
Bottom 2x Dark grey SATA3 ASMedia ASM1061 AHCI Mode


Rampage VI Apex Overclocking: Known issues

  1. After BIOS flash reset your bios date/time, crazy values can cause weird issues with certain software

Rampage VI Apex Overclocking: World Records

Intel just announced its latest X299 platform and accompanying series of high-end-desktop processors. Using the new Rampage VI Apex motherboard, the ROG Overclocking team broke a total of seven world records and captured 16 global first places on the Core i7-7740X, i7-7800X, i7-7820X and i9-7900X. They also hit the highest CPU frequency for a Intel Core i7 processor with 7.562GHz on all four cores and eight threads. Doing so required exotic cooling methods, including liquid nitrogen (LN2) and even liquid helium. (June 2nd, 2017 – ROG Blog entry)

Rampage VI Apex Overclocking records



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