ASUS ROG Maximus VIII Hero (Intel Z170) Motherboard Review (Page 3)

Circuit Analysis

The motherboard looks really nice when it's nude, and the VRM MOSFETs and MLCCs have a nice contrast. I am getting a little carried away here, but the block diagram on the right shows how the bandwidth is routed throughout the motherboard.

There are four major input rails to the CPU for Z170; VCC (VCore), VCCGT (Graphics core), VCCSA (System Agent), and VCCIO (CPU IO). The VCore is most important followed by the graphics and then VCCSA and VCCIO. ASUS is using an 8+2 phase design for the VCore + VCCGT. There are four IR3599 phase doublers located between the big input capacitors behind the MOSFETs, which are used to convert 4 phases into 8 for the CPU VRM. There are 10x IR3535 on the backside of the VRM and 8 of these are used for the CPU phases and 2 for the graphics two phases.

There aren't too many digital PWMs on the market for Z170, but ASUS is using this one which is very similar in size and pin count to IR's latest digital PWM I have seen on an EVGA board I have. I think ASUS is using the IR35201 which can support either 8+0 phase mode or 6+2 phase mode as it is doing on this board. It's International Rectifier's (now part of Infineon) latest and great digital PWM, and IR is well known for making some of the best PWMs for overclocking. ASUS is using the tried and true Texas Instruments NexFET CSD87350Q5D which is a 40A dual N-Channel MOSFET with support for very high switching frequencies and solid efficiency. Both the high-side and low-side MOSFET are packaged into the same IC, to help save space.

Below the CPU is a TPS51362 which is a 10A step down converter, and a VRM made up of a UPI uP1540 and some ON Semiconductor MOSFETs, the NTFSC09N is the low-side MOSFET and the NTFSC06N is the high-side MOSFET. These two power converters provide the VCCSA and VCCIO rails. Another TPS51362 is also present right below the DIMMs and it either provides the PCH with power or provides the DDR VPP rail which is a new rail for DDR power. Another Digi+ PWM (different than the main CPU PWM) is located near the memory DIMMs and two phases are used to power the memory.

Last updated: Apr 7, 2020 at 12:33 pm CDT