VRMs and overclocking features
Two features are a lot more important to overclockers than they are to regular users: the quality of the power supply and the present features that significantly improve the life of an overclocker.
The power supply of the MSI X299 XPower Gaming AC consists of a total of fourteen phases, of which twelve are directly for the CPU (Vcore). The other two phases deliver power to the system-agent and the memory. An IR35201-controller operates in 6+1 phases mode and controls the CPU-phases via doublers. Per power phase a single IR3555M-mosfest with a rating of 60A is present.
ASUS mostly offers the same. It is a bad kept secret that the Digi+ ASP1405I-controller is basically an IR35201 with a different label. The Apex ‘only’ offers eight power phases, but all of them are directly controlled. Once again we see IR3555Ms as mosfets.
To start off it is important for overclockers that a motherboard offers more than enough fan headers. Some extra ventilation is never a bad thing, and having to pull power directly from the power supply is not a convenient solution. The Apex offers twelve headers, of which seven can be controlled via PWM. The other five headers always supply 12 volts. Considering the target audience and the fact that there are more than enough headers that do support PWM, we do not mind this. On the XPower we find a total of ten PWM-headers.
All of the basic overclocking functionality is supported by both boards. This includes but is not limited to turning off cores via the BIOS, reading errors from a display and reset or boot the motherboard by using on-board buttons. Both motherboards have dual-BIOS-functionality and the possibility to flash the BIOS without the need to install a CPU or memory. Both boards also have a slow mode, in which the multiplier goes down temporarily so that you can easily turn off your barely stable overclock after running a benchmark, after which you can take the necessary screenshots. Voltage measurement points are also included, but you do need to connect them to probes yourself – in contrast with the Z270 XPower MSI does not offer a useful header.
The Apex has a couple of extra features that are missing on the XPower. Next to the 24-pins ATX-connector we find four PCIe-switches, that allow you to turn off the PCI-Express X16-slots one by one. This is useful when you are debugging a 4-way SLI setup: which of the four cards is the source of the issues? The ASUS also offers an LN2-mode. In this mode the coldbootbug of the system is bypassed, which is only useful when you are overclocking with liquid nitrogen, helium or any other extreme cooling method. For those that want to overclock a Kaby Lake-X CPU, ASUS offers a special modification with a so-called DMI-pin. By placing it you unlock a voltage that connects the transfer speed of the PCIe-bus with the processor, but once again this is only relevant for extreme overclocking.
|MSI X299 XPower Gaming AC||ASUS Rampage VI Apex|
|of which PWM||10||7|
|Cores can be turned off|
|PCIe-slots can be turned off|
|Voltage measuring points|
|BIOS flash without CPU|