THE HEATSINK GUIDE - News Archive (February 2005)

Cooling requirements of the new "90nm" Opteron CPUs Monday, February 14, 2005 / Tillmann

AMD announced new Opteron CPUs made using 90nm technology today. Interesting fact: The die shrink did not always result in reduced power usage. E.g. in case of the 1.8GHz model, power usage increased to 85.3W, compared to the 82.1W of the old model made using 130nm technology. Keep in mind that the new models also have a modified core (stepping E4), which now supports SSE3 instructions. In the past, AMD CPUs typically were easier to cool than their Intel P4 CPUs, because most models had lower power output than their Intel counterparts, and could withstand much higher temperatures. This is no longer true for the latest Opteron models; AMD reduced the maximum operating temperature to 67°C. The thermal design power is 92.6 watts for the fastest 2.6GHz model. This should make the new AMD CPUs almost as hard to cool as recent Intel P4 CPUs - except for the latest "Extreme Edition" P4s, which still have the most extreme cooling requirements, at least for now. Future dual-core Opteron CPUs will also be produced using the 90nm process, and probably also be based on an "E4 stepping" core. We can therefore guess that their thermal design power might come close to the 200W margin - unless AMD has intentionally exaggerated about the TDP of the 90nm single core Opterons, to prepare server- and cooler manufacturers to the actual TDP of future dual core CPUs. In any case, dual core CPUs will take PC cooling to new realms; we can expect that watercooling will become more mainstream. It will also push the BTX form factor, which, unlike ATX, was designed with high-powered CPUs in mind. It is worth noting that IBM announced that their eServer 326 dual-socket 1U servers will be compatible with dual core Opteron CPUs. This is quite astonishing; it will be interesting to see if these machines will actually run with two dual-core Opterons, and whether it's possible to run 24 of them in a standard 19" rack, without additional spacing between the individual servers.

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