The Desktop Kabini Review Part 1: AMD Athlon 5350 (AM1) Tested

Each of these APUs features up to four 28nm Jaguar cores and a 128 SP implementation of AMD's GCN GPU. We've gone over both the Jaguar and GCN architectures in previous articles, so we won't spend a lot of time recapping them here. Jaguar is the latest in AMD's line of "cat" cores, designed to go up against Intel's Atom. GCN on the other hand is a well known GPU design from AMD as well, cut down here to fit in a much smaller die area (and thermal envelope). 

This isn't the first time we've seen this Jaguar + GCN combination of course. Kabini first launched as a notebook APU nearly a year ago. Architecturally we're looking at the very same SoC, even down to running at the same max clocks and at the same TDP. The big difference is what we have here today is socketed and targeted at the desktop.

The Athlon and Sempron brands are back and used for AM1 Kabini. The most expensive AM1 APU is the $55 Athlon 5350, a quad core SoC running at 2.05 GHz with a 2 compute unit GCN GPU (128 SP) running at 600 MHz. All four models will have an official TDP rating of 25W, suggesting that they are all the same die and merely binned according to performance.

While the APU costs are low, it's actually the motherboard costs that are most impressive. AMD expects mini-ITX and micro-ATX AM1 motherboards to retail for between $25 - $35. At the low end of the spectrum that means you could be looking at a fully integrated desktop platform for less than $60. Obviously you have to add in the cost of memory, storage, PSU/chassis and heatsink/fan but we're still dealing with an extremely low cost solution.

The real value in having a socketed processor is being able to upgrade the chip without incurring the cost of a new motherboard down the road. Unfortunately AMD isn't saying anything about what future APUs will support Socket-FS1b, so for now all we have is what's in the table above. Given the BGA compatibility between Kabini and Beema, I'd assume we might see a Beema FS1b upgrade at some point. However what comes after that remains to be seen.

Historically AMD has done a good job of maintaining backwards compatibility with sockets for as long as possible, the one challenge being shifts in memory technology. With DDR4 expected to ship at the high end later this year, the DDR3 based FS1b platform should at least have some life in it from a memory compatibility standpoint.

The Platform, Socket & Motherboards

As you can see, Kabini provides a good amount of IO. The Gigabyte board includes a single PCIe x16 slot (x4 electrical) and two x1s. You also get two USB 3.0 ports and two USB 2.0 ports on the back header, although the APU itself can support up to 8 USB 2.0 ports. There are also two 6Gbps SATA ports down on the board, the maximum supported by Kabini.

The audio solution has to be cheap to be viable, and we get an ALC887 Realtek codec, which is actually higher end than I expected. Realtek are said to offer a discount when an audio codec and network controller are bought for the same product, so it is no surprise to see a Realtek NIC equipped here. 

Because AM1 is a drive to low cost platforms, I do not see many motherboard manufacturers taking advantage and producing works of electrical engineering art. When the most expensive APU you can purchase for a platform is $55, when a motherboard manufacturer starts considering extra controllers or fancy features, the cost/benefit analysis might go out of the window. An extra USB 3.0 controller might add $0.75 to the bill-of-materials, require extra validation and optimization, then add a final $2.50 to the end-user cost (or $4 after retailer markup). After speaking with Patrick from ServeTheHome about the platform, there is certainly scope for adding several NICs to the motherboard and combining its use both as a PC and a router, however none of the motherboards being released with AM1 at launch seem to have more than one.

I was told by AMD that AM1 systems should support memory overclocking above the verified DDR3-1600 speed. This should allow the integrated graphics to stretch its legs a bit more despite the presence of a single channel memory controller should a system integrator consider buying faster memory. Unfortunately at least the Athlon 5350 seems locked to a max multiplier of 20.5x, so there's no hope for easy overclocking of this part at least.

On day one, motherboards should be available from the following vendors:

Once the products are in the market we will attempt to go over them all in one of our motherboard previews, and perhaps a few in full reviews. 

With a new socket comes a new heatsink mounting system. Although the rest of AMD's desktop sockets still rely on a latch + lever retention system, Socket-FS1b moves to a push-pin design similar to what Intel uses on its motherboards (albeit with fewer mounting holes, and much simpler mounting/removing due to lower retention force requirements).

Most AM1 platform motherboards will be similar to what we have here. Some will ship with DisplayPort/DVI, and others might have an extra USB3/SATA controller. I doubt we will see any with audio codecs above the ALC892, or Killer NICs, although there might be an Atheros in the mix.