Socket AM1 Platform
The new Socket AM1 platform launched especially for AMD’s affordable energy-efficient processors features a new socket which is not compatible with anything other than the new Kabini series. It had been codenamed Socket FS1b in technical documentation.
The processor socket resembles AMD’s “full-size” ones in design but has fewer contacts (721) and takes less room on the mainboard.
To test the new platform we will use MSI’s mini-ITX AM1I mainboard. Its design is going to be typical of all mainboards for the desktop Kabini series.
AMD wants mainboard makers to produce micro-ATX Socket AM1 products as well, but it is such compact 17x17cm models that are going to be the most attractive in terms of price. The MSI AM1I comes at a recommended $36, for example. You can guess the reason by just looking at the photo. Socket AM1 processors allow building very simple mainboards. Even in its desktop incarnation the Kabini remains a system-on-chip, integrating all basic controllers (DDR3 SDRAM, PCI Express, USB and SATA). Thus, a Socket AM1 mainboard doesn’t need any chipset so its entire PCB can be populated with small controllers and expansion slots.
The Kabini’s integrated controllers support the following:
- Eight PCI Express 2.0 lanes which can be wired to a PCI Express slot or external controllers, e.g. a wired or Wi-Fi network controller
- Two USB 3.0 ports and eight USB 2.0 ports
- Up to four digital display outputs with 4K resolution (DVI, HDMI, DisplayPort) and an analog display output
- Two SATA 6 Gbit/s channels without RAID functionality
- SDXC UHS-I interface with up to 104 MB/s bandwidth for SD memory cards
Building on this foundation, MSI offers a mainboard with two DDR3 SDRAM slots (in single-channel mode), one PCI Express x16 slot (in x4 mode), and a mini-PCI slot (for a half-size card). The mainboard also carries two SATA 6 Gbit/s ports and two headers for four additional USB 2.0 ports. You can connect serial and parallel ports as well as a TPM module. There are two fan connectors (the CPU one only supports 3-pin connection).
On the mainboard’s back panel, there are two PS/2 ports for mouse and keyboard, video outputs (D-Sub, DVI-D, and HDMI), two USB 2.0 ports, two USB 3.0 ports, an RJ-45 connector (Gigabit Ethernet) and three analog audio connectors. The LAN interface is based on a Realtek RTL8111G controller whereas the analog audio is based on an 8-channel codec Realtek ALC887. It must be noted that the mainboard can output to two displays concurrently in clone or desktop extension modes. Resolutions above 1920x1200 pixels are only supported via HDMI connection.
The MSI AM1I has a 3-channel voltage regulator, which should be quite enough for processors with a peak power draw of 25 watts, especially as the Socket AM1 platform doesn’t provide any overclocking capabilities. The top memory frequency you can choose in the mainboard’s BIOS is 1600 MHz. The processor’s frequency multiplier cannot be increased and there are no options altogether to change the base clock rate.
Besides MSI, nearly every other brand has announced its own mini-ITX and micro-ATX mainboards for Socket AM1 processors although they had not been so eager to do so in the past. The Taiwanese firms seem to see some perspectives in the Socket AM1 platform.
The new platform brings about a new CPU cooler format with a revised fastening mechanism. Coolers for AMD processors used to be fastened to the processor’s frame whereas the Kabini cooler is secured with two plastic dowels which are inserted into openings located at two opposite corners of the processor socket. The openings are only 85 mm apart from each other.
The default cooler is a rather small aluminum heatsink with a buzzing 50mm fan that has a peak speed of 3000 RPM and is controlled via voltage adjustment. Passive cooling would be far more appropriate, yet a passive heatsink capable of dissipating up to 25 watts wouldn’t be cheap, so it wouldn’t fit well with the Socket AM1 concept. Anyway, a number of cooler makers promise to support the new format, so there will probably appear alternatives coolers in the near future.
Designing the Kabini as a processor that can be inserted into a socket only makes sense in terms of upgrade opportunities. However, the future perspectives of the Socket AM1 platform look rather vague as yet. On one hand, AMD is supposed to transition from the Kabini to the Beema design but has not yet made any statement as to their pin compatibility. It is possible that the desktop Beema will have a DDR4 controller, making the Socket AM1 platform a dead end with no upgrade options. Moreover, considering that the Kabini incorporates a South Bridge, AMD shouldn’t add or change any interfaces in its future Socket AM1 processors for the sake of compatibility. In other words, if the manufacturer wants to add more PCIe lanes, switch to a newer PCIe version, implement M.2 support or something like that, a new version of the CPU socket will probably be required.