ASUS ROG Crosshair VI Hero Extreme Overclocking Guide (Updated to v0.5)

Crosshair VI Hero motherboardThe ASUS ROG team prepared a Ryzen 7 Crosshair VI Hero extreme overclocking guide for those who wish to get the most out of their Zen-based processors. The guide was originally published by Elmor on the HWBOT forums and is shared at with explicit permission.

The original article published on March 2, 2017, was based on the guide v0.2 for BIOS 5803. On March 3, 2017, we updated the article with information from guide v0.4 for BIOS 5803. On March 23, 2017, we updated the article with information from guide v0.5 for BIOS 0902


IMPORTANT! Please update to 0902 or later ASAP to avoid bricking your motherboard.


Crosshair VI Hero Platform basics

General overclocking

  • CPU Ratio is adjustable in 0.25x steps.
  • DRAM Ratios available 1333-3200, higher DRAM frequency is achieved by increasing reference clock. Usable memory ratio depends on your DRAM
    configuration (see DRAM overclocking section).
  • Reference clock can be adjusted from 85 MHz to 145+ MHz, depending on the specific CPU/MB. It’s limited by Promontory/PCIE devices (54/55 POST code).
  • If ratio is set above default (on 1800X = 36.25x), the CPU will enter “OC Mode”  and disable CPU/XFR and any power saving or limitations.
  • Max CPU temperature before throttling is 95 °C. This means the Tctl temperature which reports the highest recorded value from sensors on the die.
  • When benchmarking use the Performance Bias option or OS tool for best results.
  • CPU temperature will read ~60 °C in BIOS due to no power savings enabled.
  • CPU Core Voltage reading from the SIO (BIOS/CPU-Z) fluctuates, use DMM for accurate readings.
  • USB BIOS Flash Back port is the bottom black port (USB2.0) at the back I/O. Filename should be C6H.CAP
  • Timer is skewed when changing REFCLK in Windows 8+. Additionally the default systimer has issues with OS ratio changes unless HPET is enabled. To summarize, always enable HPET on this platform.

PCI Express

I/O configuration

Connector Bandwidth Source Note
PCIEX1_1 1X Gen2 Promontory
PCIEX16_1 16X/8X Gen3 CPU 8X mode if PCIEX16_2 is populated or
using APU
PCIEX1_2 1X Gen2 Promontory
PCIEX8_2 8X Gen3 CPU Put VGA in this slot if pushing REFCLK
PCIEX1_3 1X Gen2 Promontory
PCIEX4_3 4X/1X Gen2 Promontory 1X mode if any PCIEX1 is populated
M.2 4X Gen3 CPU

PCI Express bandwidth when increasing REFCLK

REFCLK interval PCI Express bandwidth Real bandwidth per lane
85-104.85 MHz Gen 3 8GT/s (985MB/s) 837 – 1032 MB/s
105 – 144.8 MHz Gen 2 5GT/s (500MB/s) 525 – 724 MB/s
145+ MHz Gen 1 2.5GT/s (250MB/s) 313+ MB/s

The above values are based on the Auto-rules and are a good indication of the margins. PCI Express bandwidth values are at default 100MHz REFCLK and increases linearly when increased. From internal testing most PCI Express devices including graphics cards and storage controllers handle increased REFCLK very well. At the moment there’s no list with proven devices.


I/O configuration

Connectors Color Speed Source Note
Back top 4x Type-A Blue USB3.0 CPU Use when pushing
Back middle 4x Type-A Black USB2.0 Promontory Bottom port is for USB BIOS Flash Back
Back bottom 4x Type-A Blue USB3.0 Promontory
Back bottom 1xType-A + 1x Type-
Red USB3.1 ASM1143
Front USB3.0 header Gray USB3.0 Promontory
Front USB3.1 header Metallic USB3.1

Installing OS from USB

  • Windows 8+ installs natively
  • Windows 7 needs USB drivers slipstreamed
  • Windows XP is currently not supported. Theoretically possible to use with Standard PC or MPS Multiprocessor + add-in SATA & USB card.


All 6x SATA-ports are from the Promontory chipset.

Crosshair VI Hero DRAM overclocking


Usable DRAM Ratios

DIMMS per channel DIMM Rank DIMM Ratios
1 Single Up to DDR4-3200
1 Dual Up to DDR4-2666
2 Single Up to DDR4-2666
2 Dual Up to DDR4-2666

DRAM frequency on ambient cooling, fully stable

DIMMs per channel DIMM Rank Expected Frequency Best Case
1 Single DDR4-3300 to 3466 DDR4-3600
1 Dual DDR4-3200 (120×2666) DDR4-3300
2 Single DDR4-3000 (112.5×2666) DDR4-3200
2 Dual DDR4-3000 (112.5×2666) DDR4-3200
  • Only DRAM timings available are TCL, TRCRDD, TRCWRD, TRPT and TRAS. The only way to affect sub-timings is by lowering your DRAM ratio (essentially behaving like strapping) and increase reference clock. For example at 2400 ratio TWCL=11, at 2133 ratio TWCL=10 and at 1866 ratio TWCL=9.
  • Most CPUs have a memory “hole” where it’s unable to train memory from 3350-3450 MHz up to 3500-3600. This means you might be unable to run 3400 MHz DRAM frequency but 3600 is OK.
  • Best performance with Samsung B-die is achieved at 145 MHz REFCLK with 2400 DRAM ratio (3480 MHz) at 11-10-10-10-22 timings. Alternatively 135 MHz REFCLK with 2666 DRAM ratio and 11-11-11-11-22 timings. This depends on the CPU/MB/DRAM capability.
  • DRAM Ratio and timings are applied very early during POST before BIOS has control which might give problems when changing both REFCLK and DRAM Ratio, if you get problems because DRAM Ratio applies first use Retry button.
  • AMD has their own DRAM recovery mechanism that automatically lowers the DRAM Ratio and resets timings if DRAM training fails (F9 → 0d) during early POST). If you reset at this point you might get stuck at CF or 90 POST codes, manually reset again and the system should POST with the lower ratio and default timings. AMD CBS settings are also reset when this happens.
  • Use MemTweakIt to read out sub-timings.

Crosshair VI Hero LN2 overclocking

  • Enable LN2 mode and load the LN2 profile for a starting base
  • Platform is Cold Bug/Cold Boot Bug free, except for PCIE/DRAM issues.
  • memoryHoleUse top 4x blue USB3.0 ports from the CPU
  • Put VGA in 2nd PCIE slot if not running 3D benchmarks
  • Typically you want to start with 141 REFCLK at 2133 ratio (3000 MHz DRAM frequency) at 11-11-11-11-22 timings, CPU Core Ratio = 28, CPU SOC Voltage = 1.20V, DRAM Voltage = 1.80V using Samsung B-die memory.
  • The CPU IMC has problems with low temperatures (below 20*C) which means memory frequency will be lower on LN2. A good CPU is able to do up to 3500 MHz DRAM on LN2. An average CPU will do 3200 MHz. Really bad ones might be limited even to 2600 MHz on LN2. Additionally the behavior varies with temperature, see typical behavior in the graph to the right. Increasing the 1.8V PLL voltage can help improve this situation, as well as setting PLL Reference Voltage to 55 (best value for your setup might differ).
  • The CPU PCIE controller also has problems on LN2, typically below -120*C and especially after cold reset (power down). The behavior is like when pushing high REFCLK (getting stuck at 54/55/E4 POST codes). For best margin use 105-140+ MHz REFCLK and 1.05V SB Voltage = 1.30V, default 100MHz has problems at very low temperatures. You can also try PLL Reference Voltage under Tweaker’s paradise for improved margins, its behavior is quantized meaning several different values needs to be tested. Typically 55 is a good starting point.
  • Safe Boot is tuned to be able to POST at lowest possible temperature, recovery options under LN2 mode:
    • Safe Boot = 105 REFCLK + CBB settings + safe settings
    • 4-second Power Button = 100 REFCL + CBB settings
    • CMOS clear = 100 REFCLK + CBB settings + safe settings
  • You might get POST issues if DRAM voltage is too high (above 1.8V, stall at 54/55 POST code)

Safe Voltage Ranges

Note that the listed values are not guaranteed and only for reference.

Ambient Recommended Ambient Max LN2 Recommended LN2 Max
CPU Core Voltage 1.40V Up to 1.45V 1.80V Up to 1.95V
SOC Voltage 1.15V Up to 1.30V 1.20V Up to 1.40V
DRAM Voltage* 1.40V Up to 1.90V 1.80V Up to 1.90V
1.8V PLL Voltage 1.80V Up to 2.40V 3.00V Up to 3.20V
1.05V SB Voltage 1.05V Up to 1.40V 1.30V Up to 1.40V
1.8V Standby Voltage 1.80V Up to 2.10V 2.10V Up to 2.30V
2.5V SB Voltage 2.50V Up to 2.80V 2.70V Up to 2.80V

* Depends on the DRAM sticks, the limit is considered from CPU IMC side.

Crosshair VI Hero Common POST codes

Q-Code Description
8 Equivalent to 00 on other platforms, CPU not operational
4b/FA No DRAM detected/installed
F9(→0d) DRAM Training failed. Note that 0d is also displayed during final POST before boot.
90/CF DRAM recovery, reset to proceed
06 DRAM unstable
3b DRAM unstable, could be because of unsupported DRAM Ratio
0C Displays at runtime when CPU enters “OC Mode”

Known issues

  • After BIOS flash reset your bios date/time, crazy values can cause weird issues  with certain software
  • You might get up to 3 POST attempts in some scenarios including CMOS clear, changing CPU and sometimes when using Safe Boot.
  • If you disable SMT it will not re-enable until CMOS clear even if changing the option. Additionally S3 resume (sleep mode) is not working if SMT is disabled.
  • If DRAM Ratio is 2666 or higher TCL will be rounded to nearest even higher number (i.e. TCL=15 → 16)
  • Safe boot is not working 100% with DRAM Ratio/timings, might have to clear CMOS in some cases to restore defaults.
  • Setting SMT = Enable and REFCLK ~110 MHz or higher will cause POST loop, leave SMT = Auto.
  • Tctl temperature readings can be off on 0902 BIOS. To fix set Sense MI skew = Enabled and Sense MI offset = 272 under Tweaker’s paradise.

Overclocking Results

CPU Frequency Validation: 5802.93 MHz

Der8auer hit 5802.93 MHz validation in CPU-Z. This is currently the highest AMD Ryzen CPU frequency. More information at HWBOT:

AMD Ryzen 7 1800X at 5.8GHz

Cinebench R15: 2454 CB

Elmor hit 2454 cinebench points on launch date with the Ryzen 7 1800X clocked at 5364 MHz. At the time this was a Global First Place for the 8-core category. More information at HWBOT:

Elmor Cinebench R15 Global First Place

Cinebench R11.5: 2454 CB

Elmor hit 27.4 cinebench points on launch date with the Ryzen 7 1800X clocked at 5373 MHz. At the time this was a Global First Place for the 8-core category. More information at HWBOT:

Elmor Cinebench R11.5 Global First Place

GPUPI for CPU 1B: 2min 10.266 sec

Der8auer hit 2min 10.266sec in GPUPI for CPU 1B on launch date with the Ryzen 7 1800X clocked at 5440MHz. At the time this was a Global First Place for the 8-core category. More information at HWBOT:

GPUPI for CPU 1B Ryzen

HWBOT X265 1080P: 61.56 FPS

Massman hit 61.56 FPS HWBOT X265 1080P on launch date with the Ryzen 7 1800X clocked at 5325 MHz. At the time this was 7th place for the 8-core category. More information at HWBOT:


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