Recommended CPU Speeds & Optimal Configuration

Hello Brig

You will likely get better performance from the two dual cores versus the single quad core.

The biggest difference between the two configurations you are proposing are power costs and thermal output. It is going to cost you more to run the dual CPU configuration. The dual CPUs are 95 watt and do not have C state features that allow the processor to adjust to demand. The quad core is either 50 or 80 watt depending on whether you have an E5410 or L5410. Also, the quad core has C state transitions that allow it to idle and draw less power when it is not being fully utilized. So, you are mainly talking about running 190 watts versus 100-160 watts, and the 100-160 watt option can go lower than that if the demand for that much power is not there. Those additional watts create more heat that requires cooling, so aside from the electric cost to run the processors you also have to factor in the additional cooling costs.

If you don't care about the electric bill then you will likely see better performance out of the dual core configuration in most scenarios. In a heavily threaded application that takes good advantage of the multiple cores the quad core would outperform the dual core. It is able to multitask better than the dual cores. The bus speed increase on the quad core is not a factor in the decision. The memory and system board operate at 667MHz, so you are not getting the benefit of a bus speed increase on the quad core.

Thanks

"If I was just looking at CPU speeds alone it would seem that replacing the newer Quad Core 2.33 Ghz with the pair of older Dual core 3 Ghz CPUs would make the system run faster."

Yes, if CPU clock was your ONLY concern, then it would run "faster", but you would never ONLY worry about CPU clock cycles in the real world, at least if you do, you would have a specific reason.  If you have a single-threaded application that simply needed to crunch numbers as fast as possible, then yes, the higher clock CPU would be faster.  If you have a multi-threaded application, this will change, and if it is multi-threaded, why not get a second CPU for the 2950 II - or even upgrade to a faster CPU(s)?

Which processor models are we talking about?  It is VERY possible that a single quad-core at 2.33GHz on a 1333MHz bus will outperform two dual-cores at 3GHz.  You should be able to put G1 processors in a G2, but you most likely could not put a G2 processor in a G1 server ... however, it depends on the processor models.

"Would it make sense to make this swap?"

Without more details, I would lean towards "no", but ... it depends :)

the two dual core CPUs should probably give a noticeable performance in query execution time?

Yes, if your queries are single-threaded and max out the CPUs then the dual cores would likely be your better performing CPUs.

Great feed back from both Daniel & Flash it confirms exactly what I had thought! I just was not sure it the G1 CPUs could run on the G2 bus.

For my specific needs I am running a Postgres database on Linux in a data warehouse environment. Although database servers are multi-threaded, queries themselves are only single threaded so the usual performance observation is that the core handling the query is maxed out to 100% for the duration of the query.

So in this kind of environment it sounds like if I was running a Dev environment and trying to be as 'green' as possible I should run the single Quad core to save power, yet if I am running in a Prod environment where query execution time is most important then running the two dual core CPUs should probably give a noticeable performance in query execution time?

Thx!

Brig