The motherboard

AMD Opteron

Since I needed an AGP slot in my dual Opteron motherboard, I was left with just a few options:
   1) Arima HDAMB
   2) MSI K8T Master2-FAR
   3) I-Will DK8W
   4) Tyan Thunder K8W

Arima is not a brand name most people recognize, but this “unknown” motherboard manufacturer is responsible for some of Intel’s reference motherboard designs. They only recently have begun to target the end-user. In the Opteron workstation market, Arima was first out with the AGP-enabled dual Opteron motherboard. Indeed desktop systems from BOXX made it to market well before Apple’s G5, making the very first gaming desktop with a 64-bit CPU an AMD64 system, not the Apple. Of course, the disadvantage to being the first is that the Arima HDAMB is also the least powerful.

The Arima offers no PCI-X slots, and thus the gigabit Ethernet adapter competes with other devices on the PCI bus. You can get away with this when there are not many PCI devices, but it’d still be a consideration. Having a PCI-X based GigE chip is important for extracting the maximum performance. The alternatives would be something like Intel’s CSA or NVIDIA’s nForce3 design. The other problem with the Arima is that there are only 4 DIMM slots available.

Four versus Eight DIMM Slots

Unlike other CPUs from AMD or Intel, the AMD Opteron features an on-die memory controller. This means that the memory is attached directly to the CPU. In the Arima HDAMB, the 4 DIMM slots are attached to the first CPU only. The alternative would be to assign 2 DIMM slots to each CPU but that would create another problem: if you ran a single-CPU, you’d only have two functional DIMM slots.

Anytime the second CPU needs to access memory, it requests the data through the first CPU. Thanks to Hypertransport, the performance hit is relatively minor but it would still be faster if the second CPU could directly access memory. In theory, you might expect the 8 DIMM slots (4+4) approach to be the perfect solution but it’s not quite that simple. It’s actually fairly complex, but one superficial approach is helpful. Imagine that you’re running a single-CPU only application that needs 1.5GB of RAM. You have 1GB on one CPU and another 1GB on the second CPU. In this case, it would have made more sense to attach the DIMMS to a single CPU. In other words, the type of applications you run can have an effect, but the “right more often than not” suggestion is to stick with symmetrical memory distribution.

In case any ultra-techies out there are wondering about SMP versus NUMA, the AMD Opteron takes care of this automagically. You get full NUMA support if you need it, but during BIOS startup, there is also one global addressing physical memory space that allows programmers to treat it seamlessly as SMP.

The Tyan Thunder K8W

8 DIMM slots, 2 CPU sockets, 4 PCI-X slots, and 1 PCI slot. What more could you want?

Tyan vs IWILL

The Tyan and IWILL motherboards have 8 DIMM slots. Now, you can put 2 DIMMs with CPU 0 and 2 DIMMs with CPU 1. Each CPU can directly access its own bank of memory. The Tyan and IWILL boards are also more advanced, adding PCI-X and 4 port Serial-ATA.

Choosing between Tyan and IWILL was actually a very easy decision: driver support. The Tyan and ARIMA boards feature a Broadcom Gigabit Ethernet chip while IWILL went with a 3Com chip. With a 64-bit operating system, 64-bit drivers are also necessary; Broadcom’s AMD64 support is better developed than 3Com’s.

ARIMA offers a Promise Serial ATA chip while Tyan and IWILL chose to go with Silicon Image. Again, driver issues are key. The Promise chipsets, while very fast, suffer from poor Linux support and with AMD64 and scientific computing, being able to boot into Linux is key. The Sil3114 chip used by both boards connects to the PCI bus rather than PCI-X bus, limiting performance somewhat when all 4 drives are attached. We won’t see PCI-X Serial ATA until the Sil3124 is adopted.

Broadcom PCI-X GigE

Silicon Image 4-port SATA

The appropriate selection of S-ATA and GigE components is the level of attention that makes Tyan such a reliable choice for performance workstations and servers. Before building the system, I did the research to ensure that the onboard chips are well supported in the environments I needed. Tyan does the same thing, and so I would have been just fine if I didn’t do the double-checking.

Analog Devices SoundMax Cadenza

The Tyan K8W is also the only motherboard in this group that features the Analog Devices SoundMax CODEC. For music, the SoundMax CODEC in the Tyan Thunder K8W provides excellent quality for a no-frills on-board audio. It’s noticeably better than the Realtek on-board devices.

16-bit, 44.1 kHz frequency response curve

2P Opteron Motherboards Feature Comparison
	Tyan Thunder K8W	IWILL DK8W	MSI K8T Master2-FAR	Arima HDAMB
Dual memory banks	Yes	Yes	No	No
Broadcom GigE	Yes (PCI-X)	No (3Com)	Yes (PCI)	Yes (PCI)
SATA	Yes (4-port Silicon Image)	Yes (4-port Silicon Image)	Yes (2-port VIA)	Yes (2-port Promise)
USB 2.0	No	Yes	Yes	Yes (VIA)
IEEE-1394	Yes (Ti chip)	Yes	No	Yes (VIA)
SPDIF out	Yes	?	No	No
PCI-X Slots	4	3	0	0
Onboard Audio	Analog Devices SoundMAX	Realtek ALC655	N/A	Realtek ALC650

The biggest disadvantage of the Thunder K8W is the loss of USB 2.0 due to an AMD chipset glitch. The Arima board featuring USB 2.0 achieves this through an added chip from Via; it is unclear which chip IWILL has selected. Though this is a significant disappointment, the PCI-X Broadcom GigE chip on the Tyan is more important, and I’ll be able to get my USB 2.0 with an add-on board.

Still, it seems to me that there’s not much room for improvement in a K8W other than USB 2.0, PCI-X SATA, and if you really wanted to nitpick, IEEE-1394b. If they Tyan offered the first two, it’d be clear Editor’s Choice material. In its current state, it’s unquestionably deserving of a Bull’s Eye Award.

Dual Opteron Gaming Motherboards

Even though I’ve made a big deal about 8 DIMM slots in a high-performance workstation, if you’re just gaming, the 4 DIMM designs will probably still be a good idea. Most “ultra peformance” gaming systems still do fine with a 1GB of RAM, and 2GB is more than enough for desktop performance. Second, PCI-X makes less of a difference. We’re particularly eager to see the Tyan Tiger K8W and MSI K8T Master2-FAR reach the market. The Tiger K8W has the same Tyan reliability and careful component selection as its Thunder K8W sibling (though it uses an Intel GigE controller), but adds USB 2.0 support. The retail price is set to be half that of the Thunder K8W!

The MSI K8T Master2-FAR is also interesting as it is looking like it’ll be one of the cheapest dual Opteron solutions at just above $200. We don’t have one in-house yet, but it doesn’t look like it uses the same robust heatsink mounting mechanism as the Tyan. In addition, it only has 2 SATA ports instead of the 4 on the Tiger K8W. Both the Tiger K8W and K8T Master2-FAR support regular ATX12V power supplies along with EPS12V designs.

Lastly, we’ve all heard about the nForce3 dual boards… we’ll keep our eyes out for that.