Testing the latest x86 rack servers and low power server CPUs

Conclusion

Intel's integrated power gating allows the newest Xeons to shutdown cores completely when running idle, and this works transparent to the software. Thanks to this technology and the generally excellent per clock performance, the Xeon L5520 is the best solution in most situations where performance/watt matters. The motherboard manufacturers are still struggling with the new platform as SpeedStep is not properly supported in the latest version of ESX. However, this is a temporary situation. Both ASUS and Supermicro will solve this problem in the coming weeks.

When it comes to low power, the AMD platform is getting a little old, but it is mature at the same time. We did not have any trouble enabling PowerNow! in ESX 4.0. AMD's CPUs lack the advanced power gating features that the newest Intel generation has and the result is that AMD CPUs consume up to 20% more running idle. That makes the AMD CPUs less attractive in applications where you run mostly in idle mode. AMD Opteron EE is the CPU that consumes the least running at full load, and this will make it interesting for power limited data centers. AMD's low power CPUs will become more attractive when the new power optimized Fiorano "Kroner" platform will arrive.