Sunday, April 3, 2011

Balancing Power, Price, and Performance in the Server CPU World

For many businesses, performance isn't the top priority when it comes to selecting a server; chances are that low power and CAPEX budget are higher on the list. AMD's newest Opteron 4100 series is targetting exactly those businesses.

The 4100 is the little brother of the Opteron "Magny-Cours" 6100. The Opteron 6100 crams up to two hex-core or quad-core chips in one package. In contrast, the "Lisbon" Opteron package contains only one chip. The "Lisbon" Opteron with C32 socket thus comes with the same improvements that the Opteron 6100 had over the hex-core "Istanbul":

* Support for DDR3 memory (low voltage also supported)
* Higher HyperTransport speeds.
* Improved C1E sleep state.

The dual socket capable Opteron 4100 tries to find a place between the relatively cheap but single socket Xeon 3500/3600 series and the more expensive dual socket Xeon 5600 series. We chose three AMD Opterons and two Intel Xeons for a closer look.

The hex-core Opteron 4162 EE promises to consume no more than 32W (35W TDP), or an amazing low ~5W per core. The chip runs at a modest 1.7GHz and comes with an affordable $316 price tag. You can get a slightly faster 1.8GHz version, the 4164 EE, but that chip costs more than twice as much ($698). As we are searching for low power and inexpensive CPUs, it didn't make the cut. The only disadvantage other than the lower clock speed is the lower clocked HT3 link at 2GT/s instead of 6.4GT/s.

If that is still too expensive for you, AMD has also a quad-core 2.2GHz Opteron 4122 at probably the lowest price ever for a dual socket server CPU: $99. The CPU needs 75W on average according to AMD (95W TDP). You'll probably want to pay a little more for the 2.6GHz 4130 ($125), but unfortunately we didn't get that CPU in our labs. Adding about 15-18% to the performance numbers of the 4122 should tell you what the 4130 is capable of.

Most of you are probably looking for a good balance between power, throughput, single threaded performance, and price. The hex-core 2.1GHz Opteron 4170 HE is a good candidate at only $174. AMD promises that average power should be around 50W under load, with a maximum of 65W.

Simply stated, Intel does not like to play in those price ranges. The cheapest Xeon is priced at $188, and offers you the four cores of the E5603. At 1.6GHz, without Hyper-Threading, and with the L3 cut in half (4MB) we doubt that it will be a good alternative. It also needs a bit more power: 80W.

The only "decent" Xeon in the low price ranges is the Xeon E5606 (four "Westmere" cores at 2.13GHz, 8MB L3, no HT). Unfortunately, we didn't have this chip in the lab. To give you an idea where it would land, we added a Xeon E5506 at 2.13GHz, which is based on the older "Gainestown/Nehalem" architecture and has less L3 (4MB). Based on our past experiences you should add about 10 to 20% of performance to get an idea where the E5606 would land. In general, the Opterons will need to surpass this older chip to be compelling.

The low power Intel chips are priced a bit higher. We asked Intel, and the "slowest" low power chip they would send is the Xeon L5630. It offers four cores with Hyper-Threading (eight threads) at 2.13GHz, 12MB of L3, and consumes a very low 40W TDP. It will need to beat all the Opterons with a decent margin to justify the rather heavy $550 price tag.

In summary, it looks like AMD might have found a some unclaimed territory here as Intel does not offer low power and cheap Xeons. The question of course is whether the performance/watt/price ratio is interesting enough, and that's what we're here to find out.

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