Dual Core vs Quad Core Questions

I'm new to laptops and now that the new DV6's have come out, I have a couple of questions:

1) Is there a big difference in battery life between dual and quad cores? Anybody have any typical battery lives from experience?

2) Is there any battery life difference between a i5 and and I7?

3) Is there going to be noticeable differences in speeds between dual and quad cores when doing normal desktop applications (not video editing) and gaming (Mass Effect 2, Civ V, etc...)?

Thanks for any input you might have!

 

I do not have specific numbers, but an i5 will typically return longer battery life compared to an i7 when the remainder of the unit's specifications are similar. Switchable graphics, hard drive speeds, screen brightness, etc all can have an effect on the battery life.

Dual versus quad cores for regular applications should provide negligible speed differences. In regards to gaming applications, the quad will of course provide better performance with varying degrees depending on the game as certain games are more cpu intensives compared to others.

 

With the current generation and beyond, the only real disadvantage quad cores have is price. Previous quads were poor in the battery life department due to the fact that switchable graphics was not possible with them, but with the current generation this is no longer the case. The dual core might have slightly better battery life, but since the i7 will shut down cores and underclock to save power, I'd be shocked if the difference is much more than 15 minutes. That said, no one here really has experience with the new Sandy Bridge quads and switchable graphics, so it's hard to say for certain. Reviews have shown that good battery life is possible, though.

Most applications and games don't really use quad cores (though Civ V happens to be a notable exception and should take advantage of the cores), but more and more are beginning to use them. This is especially true of games, with most newer demanding games recommending a quad-core. That said, someone is probably going to say that dual cores are better for gaming due to higher clockspeeds. The truth is that CPU speed is rarely a bottleneck over 2GHz, and the quads are actually equal to the duals in clockspeed when factoring Turbo Boost.

 

Thanks for the info. I guess I might as well go for the Quad Core to keep it more up-to-date for a longer period of time.

I suppose if I don't like it, I can send it back and get the dual.

 

Have to disagree here.

Games universally do not take advantage of more than two cores so if gaming is your priority there's no need for a quad core chip

What a quad core does give you is flexibility and muscle for more demanding tasks. Want to surf the web or edit photos smoothly while doing something multi-threaded like ripping DVD's - get a quad core. Want to leave apps open in the background while you're gaming - get a quad core.

Battery life of quad-cores / dual-cores with current generation chips is similar for light (web) use, but under heavy use like gaming / rendering the quad core will eat battery more quickly. Under full load you're talking 35W TDP for the dual core chips and 45W TDP for quads.

 

That's why I put the stipulation that performance will vary based on the game because proper coding is required to utilize those additional cores.

Regardless, dual cores have effectively become mainstream (even in cell phones!) and quad cores are following close behind. I would assume that game developers are taking that into consideration and coding their games for multiple cores as we move forward.

 

Why wouldn't you like it? Only bad thing is they're marginally more expensive. Might as well get the dual if you think you're not going to like quads though...

Yeah, and there have been quite a lot of games that benefit from at least 3 cores for quite a while. The Xbox has 3 CPUs, and the Playstation 8, so engines designed to work on all three platforms pretty much have to be taking into account at least 3 CPUs.

 

To clarify, if I don't like the battery life. For the most part, it will be plugged in. Only during my travels in Europe this summer will there be longer periods without plug in availability, hence the desire for good battery life. I know HP says they get 5.5 hours on 6 cell. I would hate to get only 3 hours or so. (I have read some horror stories about battery life with older generation i7's and graphics cards.

 

Should be comparable unless you're doing something that really stresses it. Although I wouldn't count on a huge battery life regardless. Just know that even if it is only 3 hours, or 2 hours or whatever, it's not something that would improve switching to a slower chip, since they're able to slow down and shut off parts of the chip that aren't in use anyway.

 

That's only because the old ones had no IGP to switch to. These ones do. Also, as stated above, cores which aren't being used are shut down. That said, battery life estimates are almost always A LOT higher than real-world battery life. Don't expect more than 3.5-4 hours even with a dual core If you get 3 hours, it won't be because of the processor and the only way to get much more will be to

a.) take extremes to to extend battery life (such as turning the brightness down to minimum);
b.) buy the 9-cell; or
c.) look for another laptop with better battery life.

 

You mentioned playing Civ V. That one of the most CPU intensive games on the market today so go for the quad core if you don't mind spending the extra money.

 

since the number of cores are not 'automatically' (optimally) used within the context of a single application, things depend a lot on how a program is structured to make use of available resources. (max) TurboBoost is only attained with a single core, and scaled down when applied to multiple core situations. Sandy Bridge does a much better job doing this BTW. The point of my story, is if ALL cores are being utilized to the max, TurboBoost isn't advantageous at all ... and each core is limited to the baseline frequency. If a core task is highly CPU intensive (no breaks for video/disk operations) a dual core with a higher base frequency can be the better choice. The i7-720qm having a base freqency of 1.6 is NOT always better than a dual core with a higher baseline.

The i7-2720qm seems to be the price/performance sweet spot ... and rivals the i7-940xm. Manufacturers charge a hefty premium considering their cost of materials to upgrade (especially for chips above the 2720qm).

 

It may depend on the system (since it depends on available cooling) but like with the previous i7 parts they seemed to be able to run at at least 1 clock speed faster than the rated speed. Like in the M15x I had, if pushing all four cores hard, a 1.86GHz part ran at at least 2GHz sustained.

As of the i7 XXX parts it shouldn't really be an issue if you're running something that only hits one or two cores since under those circumstances it can overclock itself so substantially it's hitting the dual core parts' clock speeds anyway...and yeah, that's only improved with the new 32nm i7 xxxx parts.

 

You can't really compare Turbo Boost 1.0 to Turbo Boost 2.0 like that. Even with all cores active, so long as a notebook is properly cooled, TB 2.0 can allow a maximum boost of +600-900MHz (depending on the CPU, and after 25 seconds it stabilizes to around +200-700MHz, usually +500MHz with proper cooling) on all of the cores, and +800-1000MHz on two cores (again depending on the CPU). As far as performance goes, SNB quads are superior to dual-cores, period.

 

Well and I saw at least a 133Mhz overclock on the Nehalam i7s with all 4 cores engaged, so it could do it too...just probably not as much.

Even aside from that, that's really a moot point since it's only relevant looking at what they can do with 1-2 cores engaged, obviously, since dual core CPUs don't HAVE three or four cores.

 

Is there any need for a quad core if I just use the laptop for HD video/photo/editing, plus web browsing, music and MS Office type applications? No games here, and likely no need for games in the future.

 

YES! Absolutely. You probably need four cores more than you do for games.

 

Photo and video editing need a quad core and a good graphics card for best results, plain and simple.

 

Really??!?! Dang - was hoping the answer was no because we like the new Sony SB dual core CB series. 1080p screen at a good price with all the other goodies we like. I guess we'll have to wait for some more quad cores to come out...

 

Well, honestly, it might be worth it to sacrifice performance in favor of a high-res screen. Ideally, you'd want both, but a high-res screen would take priority.

By the way, have you considered the Dell XPS? What's your budget?