Board Layout

Despite having a B850 board with the same name, the Phantom Gaming B860I Lightning Wi-Fi is very different in a number of ways. The model we're looking at here looks and feels more substantial than its AMD counterpart, with dual VRM heatsinks that are linked via a heatpipe. There's a rear backplate heatsink on both boards, but here it stretches right around to cover both banks of power delivery components. The board has decent aesthetics too and certainly doesn't look like it's one of the cheaper sub $200 Mini-ITX boards out there, although it does lack RGB lighting.


With everything removed, it's clear we're dealing with a more conventional and simple PCB, with nothing too outlandish to report in terms of catering to the smaller PCB. There's also nothing by way of tool-free features and no quick-release for your graphics card, so you'll have to put your fingers to use. Thankfully there's plenty of space and even dislodging an RTX 4090 wasn't an issue.


Moving on to the features and there are three fan headers assigned to the CPU, chassis fan and AIO pump as standard, although you can swap and change assignments in the EFI to some extent, which is useful. More on that later, but in terms of power, the CPU fan and chassis fan headers are limited to 1 A/12 W, but the AIO pump header goes all out and supports 3 A/36 W, so is definitely capable of powering any AIO or even some custom watercooling pumps. Next to these is one of two 3-pin ARGB headers. These are all well-placed at the edge of the PCB, which is exactly where you want headers like these with a Mini-ITX motherboard.


It's rare you see a motherboard with an odd number of SATA ports, but while using anything SATA-related in a small form factor PC is often frowned upon as it will just add cables, it's good to see a generous three here for those looking to transplant hard disks and old SSDs. The layout does get a little cramped, with the front panel header on the left, USB 2.0 and 3.0 headers on the right, second 3-pin ARGB header and SATA ports likely meaning a more complicated cable routing experience to your typical ATX board, and this also makes it hard to reach the 2-pin thermistor header and CMOS clear header too, which will end up buried. Still, it's good to see the option of using thermal probes to measure case or coolant temperature, which is generally more critical in small cases.


There's no double-stacked heatsink here so the top-side M.2 capacity stands at one, supporting PCI Gen 5 SSDs and being equipped with a modest-size heatsink that will require a screwdriver for installation. Sadly, the underside heatsink does not make thermal contact with the SSD and given double-sided PCIe Gen 5 SSDs really benefit from double-sided cooling, this is a shame. On the plus side, there's plenty of space around the CPU socket and large AIO pumps such as those from NZXT or ARCTIC, generally sit over the M.2 heatsink and equally low-riding top VRM heatsink, which definitely can't be said for some higher-end boards. Some of these coolers even offer VRM cooling, which could extend to airflow over M.2 slots too.


The second M.2 port is, as usual, located on the rear of the PCB and is limited to PCIe Gen 4 SSDs. If you're wondering what size heatsink on an M.2 SSD you can fit here, the ATX specification minimum distance between the underside of the board PCB and motherboard tray is 6.4 mm, which leaves very little space for an M.2 heatsink, unless, as is usually the case, the CPU area cut-out allows the SSD to poke through.


Thunderbolt 4 is present by way of a Type-C port, but the rest of the rear I/O panel is quite bare, with just seven Type-A ports comprising one USB 2.0, four USB 3.0 and two USB 3.2 Gen 2. In addition to the DisplayPort out over Type-C should you wish to ditch discrete graphics, there's also an HDMI port, while the rest includes standard Wi-Fi antennas, a USB BIOS Flashback port, 2.5 Gbps Ethernet plus 3.5 mm jacks and optical out for the onboard audio.