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ASRock Fatal1ty X99X Killer/3.1 (Intel X99) Motherboard Review (Page 3)

By: Steven Bassiri from Jun 3, 2015 @ 9:10 CDT
TweakTown Rating: 93%Manufacturer: ASRock

Circuit Analysis


The VRM on this board consists of 12 phases. ASRock has focused on power density by utilizing lower profile 60A inductors and more integrated phases. The output filter is a mix of three different types of capacitors; 8x 560uF solid 12K Nichicon capacitors at 4480uF, 6x 330uF tantalum POSCAPs at 1980uF, and some ceramics. This is roughly 6460uF total and more than enough for strong performance.


The PWM controller is an Intersil ISL6379 Digitally Controlled Hybrid 6 phase PWM. There is no datasheet, but I would venture to guess that it is a 6+1 phase PWM. To get 12 phases manufacturers must double the phase count from the PWM since there is no 12 phase PWM in production for motherboards. ASRock uses 6x Intersil ISL6611A which are phase doublers with integrated dual drivers. This saves a lot of space which is important considering the limited motherboard real-estate of the X99 platform.


ASRock is using 12x FDMS3668S which are dual N-Channel MOSFETs from Fairchild Semiconductor in the PowerTrench package. They have very good thermal and current ratings at 13A/18A (high/low side) at only 2.5W which is excellent.


Each memory VRM is like a two phase version of the CPU VRM, using the same ISL6379 PWM and the same dual N-Channel PowerTrench MOSFETs for a total of three ISL6379 and 16 dual MOSFETs on the board. An MPS MPQ8632 is used for the VPP power for each set of the 4 DIMMs.


It's pretty amazing that ASRock is using the ISL6379 three times on the board, it is overkill, but should provide very nice voltage control. The memory DIMM's main MOSFETs need drivers and four tiny ones are found on the back of the board. The drivers are Intersil ISL6208.

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