The chaps over at AnandTech We take a look at two nearly identical systems, with the chief difference being the CPUs used: one uses AMD Socket-F:

Seeing as we believe that most servers do not operate at CPU utilizations levels which approach saturation, Socket-F has done very well. It is able to keep up to Woodcrest for the first 3/5 of the Load Points and with less power. Many companies will add more servers/CPUs/etc. once they are running at over 60% CPU utilization, so we do feel that the first three Load Points are the most meaningful. Yes, Woodcrest is faster, but the FB-DIMMs do serve to hinder performance and performance/Watt in our testing.

It would appear the major difference between the Opteron 285 and 2218 is power consumption. 2218 is comparable on performance but uses significantly less power at the same time. Is this any indication about what we can expect from K8L? If K8L keeps the low power requirements but improves performance over AMD's current offerings, they should be in good shape later this year.

Some might wonder if a different - read Intel - motherboard for the Woodcrest system could have significantly altered the outcome of these tests. We do not think so. Although the Intel motherboards do tend to show slightly lower power consumption, it is not a significant difference. All things considered, the Opterons are holding their own and doing very well for an architecture which is 3.5 years old. Only companies that are routinely running their servers near capacity are likely to truly benefit from an upgrade at this point in time.