The VRM (Voltage Regulator Module) or VRD (Voltage Regulator Down) is a circuit of a Z97 motherboard that supplies the main input voltage to the CPU. It does this by converting the 12V ATX supply to the desired voltage with the PWM method and the use of a controller, drivers, mosfets, chokes and capacitors. The quality and ability of this circuit is crucial to the overclockability of a processor.
Quick and dirty how-to read the table:
- Controller: You want this to be digital. It's higher precision and saves power. It may also report additional data on HWInfo.
- Controller Phases: "Real" CPU phases. The more the true phases the steadier the supply. In most cases 4 or lower isn't considered great.
- Doubler: If the board doubles the phases it gets higher current capacity, but it's better to have e.g. 8 real than 4 × 2 (given that the rest are equal).
- Amps per 6.5 Watts: This is a normalized current a MOSFET package can carry based on 6.5W Power Loss, a realistic scenario. Aim for this to be high enough. e.g. 200W power delivery on 2.0VIN will require 200/2= 100Amps split on the total phases.
- Total phase count: Shown by the amount of Inductors(Chokes).
- RAM phase count: Independent from CPU VRD, supplying power to RAM. It's often important on extreme overclocking to be higher than 1.
(to see the image enlarged: Right click->open link in new tab.)
- Also look at the updated Sin's list: http://sinhardware.com/index.php/vrm-list The original reason of the existence of this work was the lack of the updated list.
- This is not official (I mainly tried to find a way to quickly evaluate good boards), I don't try to replace Sin (neither on lists or on knowledge), and part of the info is incomplete (but I do put an "?" on any info that isn't confirmed by sources based on photographic evidence).
- The improvement from 6 to 8 true phases is lower than the improvement from 4 to 6 true phases (look at Sin's Hardware literature above for details)
- Some gigabyte boards have mosfets that are package-limited to 25Amps but because of that external limit they have only 4W heat loss (at that current) instead of 6.5W the normalized list may imply.
- You can multiply the number of total phases with the current capacity of low-side mosfets for a rough estimation of boards' total current ability.
Sources follow (whole of thread)
Gigabyte thread, and Sin posts in it: https://www.overclock.net/t/1487772/gigabyte-z97x-discussion-help-and-owners-club-soc-and-gaming-editions-also-included/0_100
ASUS ROG Maximus VII Ranger:
As with all ASUS motherboards, the ASUS Z97-A power delivery is a digital design with a DIGI+ VRM EPU controller underneath the heatsink labeled ASP1252 with four drivers and eight pairs of NXP 6030DLB/4030DLA LF-PAKs . There are also two phases for the memory with two pairs of NXP 6030DLB/4030DLA LF-PAKs controlled by a Richtek 8120 instead of a DIGI+ controller unlike the higher end ASUS motherboards. This means that memory overclocking will not be available through ASUS AI Suite, only through the UEFI. There also won’t be phase controls for the DRAM in the UEFI. The chokes are 1.2uF ferrite inductors while all the capacitors used are solid Japanese capacitors with a 5K rating at 105C. Compared to other motherboards with a 2000-hour rating at 105C (which last 200,000 hours at 65C typical), the 5K @ 105C rating translates to 500,000 hours at 65C.