12th gen intel memory overclocking voltages

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CPU voltages

VCCIN
    Generated by the motherboard
    Used by the IVR to produces other votlages on the CPU like VCCSA and CPU VDDQ
    1.8V by spec
    Doesn't really affect anything at ambient. 

VCCSA
    Internal to the CPU and created by the IVR from VCCIN
    Powers the CPU's system agent
    Raising it can help stabilize higher IMC clocks
    I wouldn't recommend going over 1.45V for long term use.
    1.35V is usually more than enough for everything.

CPU VDDQ / VDDQTX
    Internal to the CPU and created by the IVR from VCCIN
    Powers the CPU's memory controller. Has nothing to do with the RAM sticks.
    Raising it can help stabilize higher IMC clocks
    I wouldn't recommend going over 1.45V for long term use. (I might be overly cautious about this)
    1.35V is usually more than enough for everything.

DDR4 Specific Voltages

VDDR / memory voltage
    Generated by the motherboard
    Powers the RAM and CPU's IMC's PHYs
    Raising it can help stabilize higher memory clocks/lower memory timings
    1.2V by spec
    I wouldn't recommend going over 1.6V for long term use.
    Too much VDDR can cause stability issues by making the RAM too hot especially when above 1.45V

VTTDDR
    Generated from VDDR by the motherboard
    Used to terminate signals for the memory
    Lowering it can help stabilize overclocks on some memory ICs
    VDDR÷2 by spec

VPP
    Generated by the motherboard
    Powers the wordline of the memory chips
    Doesn't tend to affect overclocking in any way
    2.5V by spec
    Must ALWAYS be higher than VDDR

DDR5 Specific Voltages 

RAM  VDDQ
    Generated by memory stick's PMIC
    Powers the IO of the memory chips ("RAM talks to CPU using this voltage")
    Affects memory clocks and timings
    More is generally better
    1.1V by spec
    I wouldn't go over 1.6V for long term use. Should be kept within 100mv of RAM VDD
    DDR5 is temperature sensitive and runs hotter than DDR4

RAM VDD
    Generated by memory stick's PMIC
    Powers the rest of the memory chip
    Affects memory clocks and timings
    More is generally better
    1.1V by spec
    I wouldn't go over 1.6V for long term use. Should be kept within 100mv of RAM VDDQ
    DDR5 is temperature sensitive and runs hotter than DDR4

VDD2
    Generated by motherboard
    Powers the CPU's IMC's PHY when using DDR5 ("CPU talks to RAM using this voltage")
    Affects memory clocks and timings
    Has motherboard specific sweet spots that can be rather low on some boards
    1.1V by spec
    I wouldn't recommend going over 1.6V for long term use.   
    On many boards less than 1.45V works best.

VPP
    Generated by memory stick's PMIC
    Powers the wordline of the memory chips
    Doesn't tend to affect overclocking in any way
    1.8V by spec
    Must ALWAYS be higher than VDDQ/VDD

Note:
These voltage descriptions are based on my understanding of the DDR4/5 and intel CPU documentation available to me and my expiriences with overclocking DDR4 and DDR5 on 12th gen CPUs. There might be mistakes.

 

LGA1700 non-K overclocking

Non-K OC on LGA1700 requires an external clockgen and a special BIOS that uses the external clock gen to bypass the CPU's internal one. Without the external clockgen and non-K OC BIOS non-K CPUs are limited to BCLKs of less than 103MHz. Typically around 102.5MHz 

AFAIK ASUS came up with this workaround for intel's BCLK restrictions on non-K CPUs.

I expect intel to completely block this workaround on 700 series boards and 13th gen CPUs too. Just like they did with 200+ chipsets and 7000+ CPUs on LGA1151 and LGA1200.

ASUS non-K OC capable motherboards
Z690 Formula (BIOS on HWbot)
Z690 Extreme (BIOS on HWbot)
Z690 Apex (BIOS on HWbot)
Z690 Hero (BIOS on HWbot)
B660-F (BIOS on HWbot)
B660-G (BIOS on HWbot)

MSI boards that can support non-K OC // waiting for BIOS
Z690 Godlike
Z690 Ace
Z690i Unify (BIOS on HWbot)
Z690 Unify X (BIOS on HWbot)
Z690 Unify
No plans for further support

Gigabyte boards that can support non-K OC // waiting for BIOS
Z690 Tachyon (BIOS on HWbot)
Z690 Xtreme
Could add more Z690 ATX boards with hardware revision

Asrock
Z690 Aqua OC (BIOS on HWbot)
IDK about any other Asrock boards

HWbot forum thread with non-K OC BIOSs: https://community.hwbot.org/topic/210553-intel-12th-gen-non-k-oc-capable-boards-bios-versions/

DDR5 motherboards should come with only 2 dimm slots as standard.

 It might be a bit early for this but so far with overclocking DDR5 the main thing I've noticed is that there are far larger differences in what memory speeds can be achieved based on a motherboard's memory topology than with DDR4.

1 DPC boards like the Unify X and Tachyon easily do 6800Mbps or more.

8 layer daisy chain boards like the Master, Carbon and Aero D have hard time with more than 6400Mbps

6 layer daisy chain boards like the Aorus Pro struggle with more than 6000Mbps

Various manufacturer QVLs mostly match my expirience. 

MSI Z690 Unify X (8 layer 1DPC) :

MSI Z690 Ace (8 layer daisy chain) :

MSI Z690 Tomahawk (6 layer daisy chain) :

Gigabyte Z690 Aorus Tachyon (10 layer 1DPC):

Gigabyte Z690 Aorus Master (8 layer daisy chain):

 Gigabyte Z690 Aorus Pro (6 layer daisy chain):

Asrock Z690 Taichi (8 layer daisy chain):

 

Asrock Z690 Phantom Gaming 4/D5 (6 layer daisy chain):

The only reason for a motherboard to have 2 dimm slots on a memory channel is to allow quad rank memory configurations. Quad rank memory configurations only make sense if you really need a lot of RAM. Since DDR5 has much higher densities than DDR4 the benefits of having extra dimm slots are smaller than with DDR4. Currently the smallest x8 IC based DDR5 stick you can buy are 16GB. In dual channel that's already 32GB of RAM which is a lot of RAM for most tasks. If that's not enough 32GB dual rank dimms already exist. In the future 24GB, 48GB and 64GB dimms will be available. Obviously for workstation motherboards support for more memory capacity at the cost of memory speed makes perfect sense. However for less memory intensive users having a bunch of completely empty dimm slots that hurt memory overclocking doesn't make sense. Especially when the extra dimm slots have such a large negative impact on memory clocks. I also suspect that a 1DPC 6 layer motherboard would clock better than an 8 layer daisy chain board.