M2400: P8600 vs. T9400

I am getting really confused with this subject. I am getting contradictory advice. HP rep said, without question go with the T9400. The downside with the T9400 appears to be battery life and heat. I think the heat is a factor of the laptop design. Can anyone quantify the battery impact. Are we talking 10%, 20%... Lets take a very simple example. I am using it to watch DV movies, how much would the difference be???

Thanks,

 

The HP rep doesn't know what he's talking about. There is 130MHz and 3MB cache difference, this would probably be 5% faster on average and would be not be noticeable under normal working conditions. I don't believe it's worth $100. I don't think there will be much difference in the heat and battery life since people usually don't put the CPU on load often while on battery. The battery life difference would be at most 15 min under these conditions. If your CPU is 100% load, then maybe you will see a 30 min difference.

 

If you study the electrical specs in Intel's data sheet, you will see that the higher power ratings of the T series CPUs apply to not just the full load condition but also to the lower CPU speeds and the sleep states. For example, the maximum current at 800MHz for the P series CPUs is 17.5A but is 22.4A for the T series CPUs. My guess, without any comparative measurements, is that the T series could have 25% higher power consumption.

All the CPUs get tested during manufacture and then classified depending on factors such as power consumptions. The CPUs with the lowest power drains will go into the low power CPU bin, medium power consumption will be P series, and highest power is the T series. However, it is also possible that CPUs that meet the P series specs may be sold as T series if there's a need to balance supply and demand.

In reality, there is a lot of good / bad luck depending on the actual CPU you get. One core of my P8600 runs much cooler than the other which suggests that, between the two cores, there is a significant difference in the power consumption.

I would not lose sleep over the possible performance difference between the P8600 and the T9400. It says a lot for Intel's marketing skills that people will pay a significant price premium for such a small step up the performance ladder.

John