As we've already mentioned in the introduction the ASUS Prime X299-A motherboard
comes with a great looking design. The PCB has a matte black
finish and the heatsinks feature covers showing the ASUS logo. As it's currently the trend there is a cover in place hiding away the I/O connectors. Apart from that the PCH received RGB backlight. The heatsinks have
been shaped nicely and the whole product is good looking. The layout
has been well thought and there are plenty of useful features, like two headers to attach external USB 3.1 ports for instance, eight SATA 6Gbps ports and two M.2 Gen 3 x4 slots.
The ASUS Prime X299-A comes with a digital 8 phase power design regarding the CPU. The CPU power design is controlled by an IR35201 dual-loop multi-phase buck controller, which has 8 output phases. Every single phase is backed up by an IR3555 driver as well as one inductor. The IR3555 MOSFETs are capable of dealing with up to 60A output current per phase, which makes the power design of this board definitely capable. On each side of the CPU socked there are four DIMM slots, which are controlled by a chip that's been labelled Digi+ ASP1103. Unfortunately we can't find any details on this chip. Furthermore both groups of DIMM slots can rely on four low RDS-ON NexFETs as well as low profile inductors. VCCSA and VCCIO are controlled by a chip that's been labelled with ASP1405. On top of that there are two CSD973774Q4M NexFETs. Overall this board has been equipped with a high-quality power design.
This board has been equipped with a total of eight DIMM-slots. Officially supported is everything up to DDR4 4133 (O.C.). There is engough space between the DIMM-slots and the CPU socket which means that you wont encounter compatibility problems with big coolers even when you choose to install RAM with big heatspreaders. Also supported are Xtreme Memory Profiles (XMP) in version 2.0. However the memory configuration will depend to the CPU that you are going to use. If you will install a Skylake-X CPU then you can install up to 128GB in quad-channel, otherwise with a Kaby Lake-X CPU you can use only four banks in dual-channel up to 64GB.
The PCH as well as the current converters are being held at adequate
temperatures using passive heatsinks. The one for the current converters is made from
one aluminium block. The
PCH heatsink is
flat and it doubles up as a M.2 SSD cooler. The cooling blocks have been very well made and they're firmly attached to the board providing enough pressure on the components. The aluminium blocks feature a silver finish and apart from that there are white plastic covers. Regarding the whole Skylake X VRM temperature topic our point of view is that as long as either an 8-core or a 10-core CPU (7820X or 7900X) is not overclocked the VRM is going to be kept at temperatures, which are perfectly withing the tolerances. The individual phases are specified to operate with temperatures of up to 125°C and this value was never reached during our testing. If you do use an 8- or 10-core Skylake X CPU and you want to overclock and you prefer to keep the temperatures low we'd recommend a full-cover water block.