The Opteron 6276: a closer lookby Johan De Gelas on February 9, 2012 6:00 AM EST
MS SQL Server 2008 Power Analysis
We'll let power consumption be the final judge:
CMT vs. No CMT
HTT vs. No HTT
CMT increases the amount of power consumed by 6-10%, but only at high loads. The extra clusters probably allow the modules (as AMD likes to call the cores) to sleep more frequently at lighter loads, and we measure no increase or even a small decrease in power consumption. The message is clear: there is no reason to disable CMT when running MS SQL Server.
Hyper-Threading seems to increase the power dissipation always. At higher concurrencies, the higher performance must be paid with a 10-14% power increase, so you might consider disabling Hyper-Threading if your want to cap maximum power output for some reason (e.g. getting to close to the maximum amount of amps allowed in your rack).
MS SQL Server OLAP Conclusion
We invested 10 times more time in our MS SQL Server testing, but frankly we are glad we did. The Opteron 6174 seems to be a true champion from a simple "throughput/power at 100%" analysis, but the reality is that servers hardly ever run at such loads. Under light loads, the Opteron 6174 is either slower and consumes more power (Balanced power setting) or it consumes quite a bit more (High Performance power setting) while being roughly on par with the competition in terms of performance. At medium load, the Opterons are beaten solidly by the Xeon; the Xeon consumes quite a bit less power in "Balanced" and performs a lot better (response times).
At the end of the day, the Xeon X5650 is the better chip (especially in "Balanced" mode) but it's also the more expensive one. The Opteron 6276 price/performance/watt ratio remains quite attractive, but if pricing is taken into account everything will depend on which MS SQL Server License you will get. We will leave that analysis to other people as an economic analysis of complex, customer unfriendly licensing is definitely out of the scope of this article.