64-Bit and Dual Core Mobile Processors Guide and Which to Buy

[Dustin Sklavos]

INTRODUCTION

This is the big debate right now. It's not about shader models. It's not about battery life. It's about 64-bit and dual core. These are the big buzz words being thrown around, but what do they mean? The salesman at the store tries to sell you a Turion 64 notebook because "this processor is 64-bit!" Well what the heck is that? "This is a Core Duo! It has two cores?" So that's like...having two processors, right? So that's twice as fast?

Notebook users right now are in the unique position of only being allowed to have one or the other, a problem which desktop users handily avoided with Intel and AMD rushing out the Pentium D and the Athlon 64 X2, neither of which has bothered to grace the notebook platform except in twelve pound land monsters. So the question of "how can I be future proof?" effectively has two answers, both simultaneously correct and incorrect.

I hope this article will shed some light on what each of these buzzwords means, and which capability you should care more about. It is without a doubt - and my editor even cautioned me about this - that this will spark fevered, possibly angry debate in the responses. I sincerely hope and expect that the debate will serve to further educate us. I'm certain it will also serve to prove how convoluted and swingy this debate is, too.

64-BIT

What does 64-bit mean? Processors in the consumer market prior to AMD's Athlon 64 and Intel's more recent Pentium 4 revisions were 32-bit processors. Well, double is better, right?

Let's just get that mentality out of our heads right now. More does not necessarily equate to better. In computers, twice doesn't mean twice as fast. Two graphics processors don't make your games run 100% faster, two processors don't make your programs run 100% faster, and 64-bit instead of 32-bit doesn't make your system run 100% faster.

The best analogy to make regarding 64-bit is effectively doubling the width of a road. If a 32-bit processor (existing Intel notebook processors, some AMD Sempron notebook processors) has a lane about as wide as a bike, that basically means you can't drive a car on it. The car just won't fit through the door. So you can move bike-sized data through it. 64-bit makes the lane wide enough to fit a car. So while your bike could bring one person through the gate, the car can bring two.

64-bit also allows for calculations with greater precision and improves the amount of memory your system can address, raising the limit from 4GB to well into the terabytes. You will never need that much RAM, for at least another year and a half. (That's a joke, folks, it'll be a little while before technology can even supply us with that much RAM. Relax, your 512MB is just fine.) What the greater precision means to you, though, is that instead of fitting two people through the gate, it can now also fit one big fat guy.

Keep in mind, though, that nothing ever scales linearly with computers. While it's theoretically possible for instructions to combine when they're sent through the processor, it's worth noting that there's time that needs to be spent combining then decombining those instructions to begin with.

Here's the catch: existing programs by and large only need the bike-sized gate (that's 32-bit for those getting slightly confused by the analogy). They only use it because it's all that's ever been. Windows XP and its predecessors through 95 were all 32-bit operating systems, and the applications written for them were only 32-bit. And though there's a 64-bit version of Windows XP that allows programs to use that wider gate, it's a kludge; the operating system is still largely 32-bit and has serious compatibility problems across the board. It sees minimal support from hardware and software vendors alike, and is borderline worthless to the average user.

64-bit processors have been on the market for a few years now, with AMD pioneering them on the desktop with the Athlon 64.

Here are the processors that are able to run in 64-bit mode:

• AMD Athlon 64
• AMD Mobile Athlon 64
• AMD Turion 64
• AMD Sempron (Only some; varies between systems and is generally rarely 64-bit capable.)
• Intel Pentium 4 6xx Series and Higher

Assume any desktop processor in one of those big hulking desktop replacement systems is 64-bit (unless it's a Pentium 4 5xx series).

DUAL CORE

Dual core sounds flashy. Sounds huge. What it basically amounts to is having two processors in one. The trick is that they both use the same gate and address the same memory. Processors like the Core Duo are also substantially more complex, incorporating interesting technologies that make it less two separate processors and more a multi-threaded processor.

Okay, so what the heck does multi-threaded mean?

Basically, programs are a series of instructions that run single file through your processor, in what's called a thread. But if a processor has multiple cores, that means it can process multiple threads simultaneously.

There's a catch to this, too, though. Most applications, at least on a consumer level, aren't written to run in multiple threads. So while a dual core processor can smooth your computing experience out by running two different programs simultaneously instead of bogging up a single core by having to make those programs take turns going through, it doesn't offer much to speed up existing programs.

That said, with the advent of dual core on the desktop and now the Core Duo in notebooks, more and more programs are being programmed/patched to take advantage of multi-threading. Quake IV, for example, sees a notable performance increase on dual core processors. And many professional grade programs, particularly multimedia programs, enjoy performance benefits from having multiple cores. Video rendering, for example, can be substantially sped up on a dual core processor.

Dual core processors and parallelism (running threads simultaneously instead of sequentially) are the big thing for chip manufacturers right now since they've basically hit a wall with clock speeds and heat envelopes, and they're virtually all that's on the map for mainstream processors from either vendor in the future.

Here are the dual core processors available:

• Intel Core Duo

What? That's it? Yeah, barring Athlon 64 X2s and Pentium D XEs making it into hulking desktop replacement systems, that's it for now.

As a sidenote, what's worth mentioning is that most Intel Pentium 4 processors produced these days have a feature called "Hyper-Threading" which basically emulates having two cores on one die. Note, however, that it EMULATES. It doesn't actually have two cores, and because of this, performance benefits are modest at best. Hyper-Threading tends to smooth out your computing experience more than authentically improve performance, and in some cases (often gaming) has been known to have a small impact on performance. Because of its questionable utility, Hyper-Threading can be disabled.

WINDOWS VISTA

Most people are concerned about compatibility with Windows Vista and I don't blame them. This is rumor control, here are the facts:

Microsoft is producing multiple versions of Windows Vista, and it's my understanding that the lower class ones will be 32-bit compatible. That's really the only way I can describe 32-bit versions, too: "lower class." While not entirely accurate - these will be fully-featured operating systems - word on the street is these versions will be missing some small features that the 64-bit versions will have. These are features I suspect most common users won't ever see or care about, similar to the difference between Windows XP Home and XP Professional.

That said, while Windows XP Professional 64-Bit Edition was a miserable kludge, Windows Vista will be the authentic 64-bit McCoy.

This has, in my estimation, a major impact on computing. Why? Because while the vast majority of notebook users are still running 32-bit processors (read: we all went out and bought Pentium Ms because they are the awesome), desktops have dominated the market until only recently, and a large majority of desktops sold in the past couple of years have had 64-bit processors. More than that, the steadily increasing encroachment of AMD Turion 64 on the notebook market creates a substantial number of 64-bit capable notebook users as well.

Because of the substantial number of users that will have 64-bit capable systems running 64-bit versions of Windows Vista (which you can be certain will be packed into capable computers upon release), it's safe to say that more software vendors will start taking advantage of a ready and available platform. And while this is likely to be a gradual change, I suspect that Windows Vista is going to be the gunshot that starts the race moving.

Keep in mind this is speculation, but I think the case is there.

But what do dual core processors mean to Windows Vista? Unfortunately, not a whole lot more than Windows XP. While it's safe to assume Windows Vista will be better optimized to take advantage of multiple cores, this isn't a huge change.

Between dual core and 64-bit, it is in my estimation that 64-bit will be more relevant to Windows Vista, but please note that your existing 32-bit processor will certainly run it just fine, just not the same version 64-bit users will be running. Indeed, the 64-bit users may not see real benefits for a while, still. Like I said before, this is largely speculation. The ultimate point, however, is that a substantial 64-bit capable user base will be there, and software vendors love having a guaranteed platform.

WHEN CAN I GET BOTH IN MY NOTEBOOK?

Soon. Very soon, in fact. AMD has announced the Turion 64 X2 will be available in the second quarter of 2006 - that's mighty close, isn't it?

Unfortunately, Intel has pushed the next Core Duo - utilizing the codenamed Merom core - until at least September of this year. Worse still, while before 64-bit capability was pretty much pronounced and guaranteed, Intel has become less consistent with announcing it in Merom. While I would expect it, I can't 100% guarantee it, so don't put all your eggs in that basket.

Either way, the Turion 64 X2 will be available in not too long, and hopefully it will offer decent battery life and won't suffer early production problems the same way the Turion 64 did.

How will the Turion 64 X2 compare to existing Core Duos? Unless AMD can optimize their power consumption the way Intel did with the Core Duo, it's pretty much going to look like this: you want dual core and 64-bit, you buy a Turion 64 X2. You want dual core and battery life, you buy a Core Duo.

BUT WHAT IF I NEED TO BUY A NOTEBOOK RIGHT NOW?

Then I don't envy you.

Honestly, and I'm sure I'm going to take some heat for saying this: it's not worth buying a Pentium M notebook anymore. For casual computing, of course, even going all the way down to Celeron M and Sempron has been alright, but this article isn't really for the family members that just want to get on Yahoo! or PopCap and check their e-mail. You're planning to actually push your system.

If you want battery life, you're buying a Centrino Duo notebook, and only in extenuating circumstances (i.e. the ultraportables) do you get a Pentium M. If you want dual core, you're buying a Centrino Duo.

But if you're concerned with 64-bit processing, you're buying a Turion 64 or Athlon 64 notebook.

Personally? I think you need one or the other. So the big question is: which one do you pick?

Dual core offers immediate benefits. Multi-threaded software exists in limited numbers, but dual core processing also smooths out existing software and can make your computer feel a bit snappier.

64-bit processing is still a bit of an unknown. The foundation exists for it, but the software isn't there. Yet. And the thing is, that while multi-threading can't really obsolete single-threading (you can always just sequence the instructions into a single thread), 64-bit CAN obsolete 32-bit processing.

If I had to make an ultimate suggestion, I would suggest a 64-bit capable notebook, but note that it's a tenuous suggestion, and your needs may differ.

CONCLUSION

As you can see, this turns out to be a fairly complicated subject. Desktop users have it on easy street, but those of us in the notebook forum have a hard choice ahead of us. I think the important question to ask yourself at this juncture is:

"How long am I planning to use this notebook?"

If it's more than two years, I'd suggest a 64-bit capable notebook. If not, you'll be refreshing your notebook before 64-bit computing becomes a "yes" instead of a "maybe" and you'll be able to have both.

What's also important to keep in mind is that being on a 32-bit system isn't necessarily going to leave you out of luck. The change isn't going to be an overnight one, it's going to be a fairly gradual one. You WILL get some longevity out of it, it's just that some newer programs won't run on it. It's going to depend on what you need to run.

Again, 64-bit computing is inevitable, but the change will be gradual, so don't let this article totally put the fear of God in you. Likewise, dual core offers immediate benefits, and it IS the future (look at either chip manufacturer's roadmaps), but in terms of actually running programs I don't foresee it obsoleting single core, and single core processors will continue to be produced for some time (see: Intel's Celeron plans, AMD's Sempron plans).

Either way, with these two big transitions in the computing industry, it's a very exciting time to be an enthusiast, and in a few months AMD is going to help clear this headache, with Intel following suit. If you can wait, do so. Otherwise, I hope this article has helped you make an informed decision on your next computing purchase.

Because how long does any one of us really keep a computer before we go out and buy something new and shiny anyhow? ;)

[Andrew]

And just to clarify, as of yesterday (prior to Pulp writing this article) we're pretty sure AMD will release a dual core 64-bit processor (Turion X2) around May 9th. Now, when that processor will show up in notebooks in any type of quantity is unknown so this guide still stands as a great way to understand the benefit of each platform type and what you lose/gain with each. Thanks for putting things in more layman like terms Pulp -- you're the king of that.

[ivoloos]

Wow!
Great article!

[Metamorphical]

Nice article. Should be helpful to those who are having hard time deciding what to get or where to buy now or wait.

"Plan for the future but not at the expense of the present"-ChazMan421

[segadc]

Great article!

[Kilim]

Awesome Article.
I was about to ask the questions that are answered here

[Iskander]

Reallly good article, i specially liked the part that 64 bit CAN obsolete the 32 bit.

I think this will silence some people in this forum that were saying that dual core is more important than 64 bit, and that dual core is the future proof! (ridiculous).

Thanks for your article.

[martynas]

To: pulp, about vista:

beta 1 and ctp are 32bit. In fact i'm running beta 1 on virtual pc with specs - 300mb ram, iP4 2.4GHz, 16gb hdd, 4mb video... It runs, slow, but it runs! And with aero glass interface.

[rebthor]

If it's more than two years, I'd suggest a 64-bit capable notebook. If not, you'll be refreshing your notebook before 64-bit computing becomes a "yes" instead of a "maybe" and you'll be able to have both.

I'd put a longer horizon on that than 2 years. I think that it will be 5+ years before there is some software that will not be available in a 32-bit flavor. No one wants to kill their market too soon, so while in ~2 years (if not sooner) you will see a lot more home focused software optimized for 64-bit computing, starting with things that like to work in big chunks of data, e.g. video processing, gaming, I don't foresee them being 64-bit only, just optimized.

Where you may see some of the 32-bit software die off sooner than in five years would be in big-iron type tasks like databases, genome processing, weather simulation; but most users won't be running those on their laptops any time soon.

That being said, I agree that in the long run, if you needed a laptop today and you wanted to future-proof it as much as possible, 64-bit>dual core. But let's be honest, with the continuous dropping in notebook and computer prices, fewer and fewer users will keep a laptop long enough for it to matter.

P.S. Thanks for the great article Pulp!

[isvara_pranidhana]

excellent! you honestly and tactfully didn't leave anybody behind...and that takes mad editorial skills! it's a great article for those of us who are/were forced into buying a new rig now due to circumstances beyond our control. yes, an unenviable position... but like i say, New Every Two!