Read the article. Their conclusion is that 24 core power8 systems can beat 36 core Xeons in some important benchmarks, both in performance and power-per-dollar (but not power-per-watt). If you want to see the reason, just look at the memory bandwidth - Power8 has about double that of the latest and greatest Xeon. That's very important, especially for fixed grid computational tasks (e.g. weather, climate) that traditionally have a very low arithmetic intensity, i.e. what really counts is the memory bandwidth.

I did read the article. Power-per-dollar are the smaller 2S Xeons btw. Not the massive 36-core Xeons.

However, the memory-bandwidth argument makes sense to me. So I'll accept that as a good reason to go Power8.

> Power-per-dollar are the smaller 2S Xeons btw. Not the massive 36-core Xeons.

Could you give a quote? All I could find about performance-per-dollar was this excerpt from [1]:

> Ultimately, the POWER8 is able to offer slightly higher raw performance than the Intel CPUs, however it just won't be able to do so at the same performance/watt. Meanwhile the reasonable pricing of the POWER8 chips should result in third party servers that are strongly competitive with the Xeon on a performance-per-dollar basis.

This was in conclusion to the E5-vs-Power8 comparison. For some reason they didn't use E7, however this shouldn't change the outcome, since according to [2] the E7 is basically the same chip with the same number of cores, just with a few more features enabled (4 and 8 socket systems possible and support for more memory). So AFAIK the E5 shouldn't be looked at as a "small" version of the E7, since taken for itself in isolation for a given benchmark that doesn't have extremely high memory demand, it should deliver the same performance. Whether you need an E7 or not should be decided in terms of the architecture you want to build, not the performance you aim for.

[1]http://anandtech.com/show/9193/the-xeon-e78800-v3-review/7

[2]http://anandtech.com/show/9193/the-xeon-e78800-v3-review/3

also the code tends to be highly SIMD, code with a lot of data dependent branches benefits very little from higher memory bandwidth when the fetch latency from ram is on the order of hundreds or even thousands of cycles.

Yes that's a good point. So low arithmetic intensity + SIMD benefits POWER mostly.

Why would you have such limitations? You can install Linux on anything. This allows you to leverage better processors or get better deals.

Except Intel is significantly cheaper. I do like the other answers stated so far, but lets be frank... the typical Linux cluster of 2S Xeons is going to be much cheaper and scalable than massive 4S 144-Thread beasts.

The Xeon in the article is more expensive than POWER8. Every other Xeon is cheaper than POWER8, but if you need multi-terabytes of RAM and corresponding amounts of CPU on a single motherboard, POWER8 is cheaper than Xeon.

this topic and the power8 have come up before.. i think it boils down to what companies have already invested in. if you have a strong AIX team already supporting power/ibm infrastructure, this is great. you have one of the fastest system platforms out there.

however, if your application/workload can be distributed over multiple machines, Intel is going to eat your lunch on cost, as you can buy several of these new Xeon systems and crush it.

not all of us have the luxury of control over the software we use (many enterprise shops are held hostage by vendor software which hasn't scaled out, and continues to depend on scaling up, because distributed is hard)

You can throw a lot of CPU power at your Websphere apps and do things like lease capacity on demand. It's useful in some business models. Power8 cut the power/cooling requirements dramatically.

If your employer historically likes IBM, it makes sense. I don't think they have any new customer acquisition.

3rd party OpenPower Motherboards are still only sampling for POWER8, so it really hasn't been fully birthed yet.