Hardware Unbox, a popular channel at Youtube recently tested the VRM quality of a number of $200 AMD X570 based motherboards. The boards in no particular order are the ASUS TUF Gaming X570 Plus, Gigabyte X570 Aorus Elite, ASRock X570 Steel Legend and the MSI MPG X570 Gaming Edge WiFi.
Before the test proceed, Steve provided a VRM design overview of each motherboards. Other brands were using phase doublers, while the TUF Gaming board from ASUS uses a more traditional approach. ASUS just tripled everything for each phases rather than adding a doubler IC on top of the power stages.
Other stuff that Steve checked out is also the physical design of each motherboard’s VRM coolers. The MSI MEG X570 Godlike for example, which is one of the best his recent top-end VRM tests features a heat-pipe enabled design. Similar to that of the MEG X570 Ace we’ve tested before.
The initial test with the Ryzen 9 3900X showed that the Gigabyte X570 Aorus Elite performed the best with a 57ºC MOSFET and 63ºC backside temperature. The MSI motherboard performed the worst here with scorching hot values.
At 4.3GHz with 1.4v at the vCore, the ASUS TUF Gaming X570 Plus took the top spot with the best temperature output. The MSI board on the other hand is still the worst out of the bunch.
Finally, we get to see how the sub $200 USD motherboards stack up with the rest of Steve’s tested X570 motherboards. The ASUS TUF Gaming motherboard with a true 4 phase design sure is a budget champ by the looks of it.
Clearly, the tests done by Hardware Unboxed shows that a simple 4 phase VRM could match or even beat motherboards with higher phase counts. Quality over quantity I suppose is still the name of the game when it comes to components. Shocking.
The TUF Gaming X570’s 6 layer PCB is a factor on why it performs well at VRM testing even if it uses a 4-Phase PWM controller for its 4×4 SiC639 50A DRmos array. Mosfets dissipate more heat at the PCB pad side, as compared from the epoxy top in where thermal conductivity is not that great (You can see International Rectifier mitigating this issue with the IR3575, which has an exposed top side pad which conducts heat very well to a heatsink.).
Meanwhile, the Gigabyte Aorus X570 Elite uses an ISL69147 PWM controller which runs a doubled 6+1 (12+2) PWM scheme (coupled with ISL6617A pwm doublers that can do current balancing) for its SiC634 DRmos array, but only has a 4 layer PCB. The thinner PCB can explain why the Aorus Elite Performs worse than the TUF even if it has a 6+1 PWM controller coupled with PWM doublers.
The Vishay SiC634 and SiC639 does not differ too much for a noticeable performance difference(Although the SiC634 is a tiny bit more efficient), but the SiC639 has integrated thermal monitoring and shutdown capability compared to the SiC634 that relies on the PWM controller to do Thermal monitoring and fault protection (which the ISL69147 PWM controller supports).
It is surprising why Asus didn’t expose the VRM temperatures to the user when the SiC639 already has support for it.
I have no idea on what is the VRM switching frequency that the Aorus Elite runs at, and maybe Gigabyte runs more aggressive VRM switching that gives better transient load response at the cost of more heat.