loomis

What is the difference between an i3 and i5 processor? Speed? Reliability? Is the i5 worth a price premium?

I am not a gamer. I use my laptop mostly for web surfing and occassional word processing.

TIA.

wiredboy10003

Look here:

http://www.brighthub.com/computing/h...les/65861.aspx

Efrem

Three main differences:

1. The i5 has four cores, so it can run four programs at the same time. Taking advantage of this requires you to have four programs that want to run at the same time, or alternatively one program (such as Photoshop) that can split its work into four parallel threads. (Useful for applying an edit to a large photo.)

The i3 has two cores. It also has something called "hyperthreading," which lets one core run two programs, so it looks like four cores - but this is less useful than four physical cores. It matters only when your workload can take advantage of more than two cores.

2. The i5 has Turbo Boost, which lets it run faster than its advertised speed under heavy load (until it starts to fry the machine, at which point it slows back down). The i3 doesn't.

3. The i3 is cheaper. It definitely gives you more "bang for the buck" at the chip level, since it was priced to compete with AMD's low-end offerings. Is the system-level price difference enough to matter? That's your call.

There may also be a clock speed difference when comparing two specific computers, but both chips are available in an overlapping range of speeds.

BTW, if you look this sort of thing up on the Web, be sure to get current info. The original Core i3/i5/i7 line was streamlined after its original announcement. The original line-up, for example, included two-core i5s. Confusing? You bet!

Added in edit: the article linked above, posted after I brought up the original thread to answer, is pretty good.

nkedel

No difference in reliability. Potentially quite big difference in speed, but if you're looking at the main laptop models (not the ultra-low-voltage ones in subnotebook/ultraportable/"netbook+" models) then you are very unlikely to notice the difference. There are some slight program-compatibility and battery-life reasons to go with the higher end ones, but in general they are not compelling for most people.

HOWEVER, If you need a machine with a ULV processor, for either size or battery-life reasons, I would avoid the i3s.

Let me try to decode the differences from here. Here are representative i3, low-end and mid-range i5s (400 and 500 series)
http://ark.intel.com/Compare.aspx?ids=43529,47341,43537,

The main difference is lack of turbo boost on the i3. On the i3-350M (representative general laptop model) the base speed is 2.26ghz which should be fine for general use. The i5-430M has the same base speed and can get a slight bump to 2.53ghz. The i5-520M has a slightly higher base speed but can get larger but not huge bump (nearly 25%) to 2.93ghz.

If you have integrated graphics (not much reason not to, unless you game or run 3D apps) then the built in graphics are a little faster on the i5 (not much reason to care IMO; if you cared, you'd get discrete graphics.)

No other differences between the i3-350m and the lower end i5 series (i5-430m) ... the i5-520M (and higher end 500-series models, and i7s) add these three things:
* Intel® Virtualization Technology for Directed I/O (VT-d)
* Intel® Trusted Execution Technology
* AES New Instructions
...and if you don't know what they are, you don't need them. Indeed, in the first two cases, if you don't know what they are, you probably want to leave them turned off in the BIOS even if you have them.

Now compare 3 similar ultralow-voltage processors:
http://ark.intel.com/Compare.aspx?ids=49665,50026,50028,
...on these, it should be immediately obvious from the base and turbo clock speeds (1.33ghz) that turbo makes a much more significant difference (60% on the 560UM, 40% on the 470UM) while the i3 is stuck at its basic maximum. Even with the Core i3/i5/i7 being faster than a Core 2 at the same clock speed, I do not think the base speed of 1.33ghz is likely to be a comfortable "general purpose" machine for most people, and IMO unlike on regular laptops (where it is only a "nice to have") on ULV machines the turbo feature of the i5 (and i7) makes the difference compelling.

nkedel

Unfortunately, several things this article says are specific to desktops and are incorrect for laptops.

The OP was asking about laptops; all mobile i5 processors are dual-core (even with the upcoming -2xxx series.) For laptops, quad cores generally available on PCs right now are only available on a handful of very-battery-unfriendly i7 models (most mobile i7 models are dual core) -- with the -2xxx series (basically still "upcoming" although a few models are finally trickling out), roughly half of the models will be quads. Easy to spot in the model number as it's i7-2xxxQM rather than i7-2xxxM.

On the desktop, with the more common/older models the i5 can have either 2 cores (-6xx series) or 4 (7xx series) - both of which are still on sale. When the new -2xxx series starts selling in quantity in new systems, you're correct that virtually all desktop i5 processors will be quad core.

PTravel

A clarification: a single program written for a multi-core CPU can run parts of itself on each core, resulting in a much faster experience. Adobe Photoshop and Adobe Premiere are two programs that support multi-core CPUs.

DeoreDX

Honestly for what you just mentioned my $500 Asus K50 Core 2 T4500 laptop runs just as good as my $2k Dell Mobile Precision M6500 w/ i7.

nkedel

To a lesser extent, the same is true for hyperthreading ("virtual cores"; dual core i3/i5/i7 have 4, most quad-core i5/i7 have 8)... for those whose experience with this was in the underwhelming form it took back in the Pentium 4 days, it's worth revisiting.

I'd expect it would. Not likely to be as good on battery life as comparably-clocked i3 or Core 2 Duo of the same generation, but otherwise more than quick enough for general use.

PTravel

Good point. It's a huge difference now for computation-intense programs. I make regular use of Photoshop and Premiere, as well as Adobe Audition for sound recording, editing and mixing. All of these programs have to render their output and the difference running on quad-core machines, versus single-core, is beyond dramatic.

bigguyinpasadena

This thread exemplifies once again why I feel the FlyerTalk Technology forum is visited by the friendliest and most helpful folks of any IBB I visit.
Thanks to all of you who make that happen ^

nkedel

I'd imagine many tasks with those programs scale almost linearly with the number of cores; it certainly does with most the open-source video software I use. (I actually use Photoshop a lot, but rather shallowly; it was fast enough for the way I use in on my 2006-vintage dual core laptop.)

Hyperthreading doesn't improve performance as much as doubling the number of real cores does, but for heavily parallelizable tasks the speed improvement can be pretty dramatic by other standards -- around 35% faster doing x264 encoding, give or take, on an i5 dual core compared to hyperthreading turned off, and some of the DB workloads at work have seen larger improvements than that.

loomis

The OP here. Thanks for all of the great feedback!!

I decided to spend the extra $100 and get a (Toshiba with the) i5 processor. It bugs me when my existing laptop gets bogged down when multiple programs are running at the same time. So far, so good.