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DDR5 memory, as you know, has chips for power management on the module. Each memory carries its own power management IC (PMIC) responsible for reducing the 5V input from the motherboard to the required DIMM voltages. PMICs normally come in a variety of qualities. Designated for the high performance memory kidollar series, they are natively configured to allow manual control of voltages. However, non-overclocked memory modules have hardware locks (aka Safe Mode) PMICs for 1.1V output. Fortunately, this constraint can be ascribed to a built-in circuit. The circuit does a bit change to increase the low-level PMIC resolution from 5mV to 10mV, resulting in a higher value for a given VID. The UEFI BIOS comes pre-coded to handle this upgrade for you.

Most ASUS motherboards have the necessary circuitry to enable voltage control on constrained PMICs. Additionally, additional hardware has been added that allows PMIC voltage changes to be applied without power cycling the motherboard. All current PMIC editing parameters are included in UEFI.

Two main channels (DRAM VDD and DRAM VDDQ) have been added to the main UEFI menu to simplify the setup. Description of each parameter is in the right pane of UEFI and Other PMIC options are in the Advanced Memory Voltages menu.

DDR5 memories that we overclock to 5600 MHz can reach much higher read/write speeds.

Configuring Memory Slots

There are two memory controllers inside Alder Lake processors. Whether single-row or dual-row, a DDR5 DIMM is configured as dual channel. In this context, motherboard memory slots are assigned as follows:

  • MC0 D0 (Memory Controller 0, DIMM 0): Slot 1
  • MC0 D1 (Memory Controller 0, DIMM 1): Slot 2
  • MC1 D0 (Memory Controller DIMM 0): Slot 3
  • MC1 D0 (Memory Controller DIMM 1): Slot 4

When using dual DIMMs, placing DDR5 modules in slots 2 and 4 (preferred over slots 1 and 3) results in quad-channel operation. It should also be noted that DDR4 memory is limited to single or dual channel operation only.

DDR5 Memory Voltage Channels

The table below shows the voltages that are important for overclocking DDR5 memory:

PMIC Parameter Useful for Overclocking? Recommended
Memory VDD Voltage: Yes 1. 25V
Memory VDDQ Voltage: Yes 1. 25V
Memory VDDP Voltage: No
Memory VDD Switching Frequency: Not much help
Memory VDDQ Switching Frequency: Not much help
Memory VPP Switching Frequency: Not much help
Memory Current Capability: Not required

Memory controller voltage setting.

CPU Parameter

System Agent (FIVR) Yes 1. 25V
Memory Controller Voltage (External) Yes 1. 25V
Transmitter VDDQ (FIVR) Yes Setting as VDD or VDDQ*

DDR5 Memory Voltage Tips

  • Some memory ICs don’t like 1.25v MC VDD, while other types need it to get higher frequencies.
  • Basically, 1.25v on both VDD and VDDQ for Hynix, 1.25VDD+1 for Micron. 35VDDQ and 1. 35VDD+1 for Samsung. Run at 35VDDQ and leave the rest at Auto settings.
  • Another strategy worth trying for overclocking is to synchronize DRAM VDD with MC VDD and TX VDDQ with DRAM VDDQ.

DDR5 Gear Mods

  • There are three DDR5 Gear modes available, 1, 2 and 4. Also, each mode has different frequency and rate limitations.
  • Gear 2 is recommended for default and general use.
  • Gear 1 is currently not working.
  • Gear 4 may cause some performance issues.
  • Gear 2 requires a DRAM ratio to be divisible by 2, while Gear 4 requires a DRAM ratio that is divisible by 4.
  • Single TCL and TWCL values ​​not working. Only use even numbers.
  • The default DRAM-BCLK ratio is set to 100:100 for DDR5.
  • The 100:100 and 100:133 DRAM ratios perform equally well.

Gear 2 Parameter Guidelines – Maximus Extreme Series

Modules Fmax VDD VDDQ TXVDDQ MC VDD SA Can it run 1T?
2* Hynix SR 6400 1. 3 1. 25 1. 25 1. 25 1. 25 Yes
4* Hynix SR 6000 1. 2nd 1. 2nd 1. 2nd 1. 2nd 1. 25 No
2* Hynix DR 6200 1. 3 1. 25 1. 25 1. 25 1. 25 No
4* Hynix DR 5800 1. 2nd 1. 2nd 1. 2nd 1. 2nd 1. 35 No
2* Micron SR 5400 1. 35 1. 4 1. 4 1. 34 1. 2nd No
4* Micron SR 5200 1. 25 1. 25 1. 25 1. 25 1. 25 No
2* Micron DR 5200 1. 25 1. 25 1. 25 1. 25 1. 2nd No
4* Micron DR 4800 1. 2nd 1. 2nd 1. 2nd 1. 2nd 1. 35 No
2* Samsung SR 6400 1. 435 1. 435 1. 435 1. 34 1. 25 Yes
4* Samsung SR 6000 1. 35 1. 35 1. 35 1. 25 1. 25 No
  • Certain Samsung or Hynix-based memory modules may run at DDR5-6000+.
  • When overclocked to the limit, Micron-based memory modules tend to pass stress tests but may cause blue screen errors when the system is idle.

Advanced Settings

Vcore Settings

Core Voltage Suspension is a ROG-exclusive function first introduced in the Crosshair VIII series. The same functionality is available in the Maximus Z690 series. Core Voltage Suspension allows the definition of upper and lower limidollarser for Vcore and is particularly useful for VID mode.

  • Voltage ceiling determines the upper limit, and the Voltage base determines the lower limit.
  • Default Voltage base is 0V (ground). The value can be increased if the voltage is insufficient for stability while the CPU is in a low power state.
  • Default Voltage ceiling is 1.55V. This value can be reduced while the Vcore is in Adaptive Mode.
  • CVS has two modes: static and amic. amic mod allows you to create a V/F curve.

Intel CVS – Dynamic V/F

CVS amic mode provides precise control over core voltage in relation to core temperatures, allowing operating frequencies to be optimized for any workload. You can see the details about CVS in this YouTube video.

If used as follows, ceiling and floor voltages will change amicably with CPU temperatures:

  • Set Floor Low VMin below Ceiling Low VMax.
  • Set Floor Hot Temp slightly higher than Ceiling Hot Temp.
  • Set Floor High VMin lower than Ceiling High VMax.
  • Set Floor Cold Temp slightly lower than Ceiling Cold Temp.

CVS – OCTool

Finally, you can also use ASUS OCTool to adjust CVS values ​​in real time.

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