How to compare old CPU to new CPU? [closed]

Question

I hope this question doesn't get closed at once :)

I have an old laptop, a Compaq NC4200, which is going its final laps around the track these days. Battery is dead, and everything kinda runs slow. It also has only 1GB of memory, and even though I don't know if it can take more, I probably wouldn't be able to get hold of any that matches without having to special order it.

The size, however, has been ideal for my usage pattern, so I'm looking to replace it with a similarly sized laptop, at least in the same size category.

However, it's been a while since I tried keeping track of CPUs, so I have a question.

The old laptop has a Intel Pentium M 760 1.86GHz processor.

One laptop I found online has a Intel Pentium SU4100 1.3GHz dual-core. This type of processor seems to be quite common in the price and size-range I've been looking.

What kind of relative performance boost could I expect from the old one to the new one? I am not expecting a "about 7.45x speed", but some indication would be nice. For instance, dual-core tells me it might be akin to 2.6GHz, but I assume I can't simply compare 1.86GHz to 2.6GHz and expect the new one to run about 1.4x as fast, I expect more these days. Or is that unrealistic for this kind of processor? Do I need to up my price range and go for a 2+ GHz processor?

Answer 1

The SU4100 is based on the Penryn-3 Mobile, so it will have a faster Front Side Bus and slightly higher per-cycle instruction processing efficiency than the older Pentium M architecture. This would allow a single 1.3GHz core to keep up with, or surpass, the older 1.86GHz Pentium M.

Add in the second core, and the system will be more responsive and capable when running more than one application, if not actually faster when running only one application.

In other words, you will have a more responsive and capable system, especially when multitasking, but it may not run any single app alone faster than the old one.

Answer 2

The Passmark CPU Benchmark list gives the Pentium M a "CPU Mark" rating of 471, and the SU4100 a rating of 986, so according to their benchmarks, the new chip is about twice as fast.

Answer 3

You'll probably find having more RAM and a faster drive will make more difference on most day-to-day activities (office apps, basic development, simple games) than the CPU speed - tasks will hit the disk less (either due to not needing to swap or due to data being in cache in RAM) and when they do they'll get a faster response.

For web browsing you might not notice a lot of difference unless using very heavy sites (those that use large pages and/or lots of scripted page modification), though page rendering for complex content will no doubt "feel" snappier.

This is assuming you'll not be upgrading all your apps to newer and more resource hungry versions of course.

Each core in a new CPU will do more work per clock tick than your old PM in most use cases as they have new tricks internally, will have much more L1 and L2 cache, and when they need to hit main memory they'll be served by a faster CPU<->RAM bus - so I'd not be surprised to find a single core of the new chip to be as fast as your old one if not faster.

As for dual core speed: this is only really relevant if running multiple processes/threads at once that are actively eating CPU time. For one single threaded application the multi-core benefit is not relevant (though will make a small difference even in that case as the many background processes of a modern OS are mean you are never running just one single thread).

What ever new CPU you get though I would expect it to be noticeably faster than your old one and will use less power than it when doing the same things (so making less heat and allowing the battery to last longer), and (possibly more significant depending on your use of the machine) the extra RAM you'll find in a new machine (most come with at least 2Gb these days, 3Gb and 4Gb not being uncommon even in some relatively low priced ranges) will make quite a beneficial difference.