Duo-core or Quad-core?

[-Entropy-]

Hi. Hoping the more "tech-savy" of you out there could help me out. Thinking about buying a new computer and trying to decide on getting a duo-core or quad-core processor. Which is better for video conversion? A duo-core with a higher GHz (2.66 or 3.06) or a quad core with a lower GHz (1.73)? I've heard that the quad-core really only comes into play if/when you want to run other programs/applications while another one is running at the same time, but if you just plan on running your video conversion program and leaving it, the duo-core with the higher GHz is better. Anyone know more about this? Would appreciate any information. Thanks...

[LoRd_MuldeR]

If you targeting for video encoding, then go with a QuadCore! Good video encoders, such as x264, will be able to leverage four, eight or even more cores!

So for the task of video encoding a QuadCore is about 2x faster than a DualCore of the same generation and clock-speed. However other applications will rarely use more than a single core.

Also be aware that the new Nehalme's (Core i7 or Core i5) use a technique called "TurboBoost", which can put individual cores to sleep and then overclock the remaining ones.

Hence the QuadCores of the latest generation finally will give optimal performance for both, multi-threaded and single-threaded application. There's no reason to stick with a DualCore now.

(BTW: Making your complete text big and italic doesn't improve the readability ^^)

[mariush]

(in the specific case in your comment) The one that overclocks higher.
It also depends on the type of content you wish to encode. If you'll use Avisynth with tons of filters and processing that serves only 5fps to x264, than you can have 16 cores, you'll still encode at 5fps.

Usual applications/programs seldom need more than 2 cores to run perfectly. A quad core or better is usually used for encoding videos.

[LoRd_MuldeR]

(in the specific case in your comment) The one that overclocks higher.
It also depends on the type of content you wish to encode. If you'll use Avisynth with tons of filters and processing that serves only 5fps to x264, than you can have 16 cores, you'll still encode at 5fps.

Unless you are using extremely slow Avisynth filters (or slow pre-processing in general), the video encoder will always be the bottleneck.

Also it should be noted that many Avisynth filters are multi-threaded nowadays and hence will benefit from any additional CPU core they can use.

And even if they are single-threaded, you may still use Avisynth-MT to leverage multiple cores for Avisynth processing.

Usual applications/programs seldom need more than 2 cores to run perfectly. A quad core or better is usually used for encoding videos.

That was before Nehalem (Core i7/i5). Thanks to "TurbBoost" the latest QuadCores can put two or three cores to sleep and then overclock the remaining two/one core(s).

This way the Nehalem QuadCores can reach higher clock-speeds and performance for single-threaded applications than any DualCore you could buy before!

So if you can effort a Core i7/i5, there's no reason to think about a DualCore nowadays. But if you are looking for a "cheap" solution, it may make sense to buy fast DualCore.

However if your primary target is video encoding, which most likely does benefit from additional cores, I'd definitely go with a QuadCore - even if it's not a Core i5/i7 ;)

[Blue_MiSfit]

Quad core, hands down :)

Get a Core i7 with Hyperthreading if you can afford it. Otherwise a Core i5 or a Phenom II are both excellent choices!

If you're on a really tight budget, the Athlon II X3 is a great choice as well, and can usually be unlocked to use all 4 cores on a decent motherboard - though it's not guaranteed.

Quad core FTW. I hate to think of anyone doing encoding on anything slower :p

~MiSfit

[-Entropy-]

Okay; so i'm getting "go for the quad"; got it. I think thats what i'll get then. Just another quick question so I can try to understand the dynamics going on here. Is the listed GHz "per core" or "total"? Meaning - Does a 1.73 GHz quad-core beat out a 3.06 duo-core because the quad-core combines to 1.73 x 4 (6.92 GHz), vs 3.06 x 2 (7.20 GHz) for the duo-core? One would think the 3.06 GHz beats out the 1.73 GHz, unless they would combine/multiply in some fashion (per core). And even then, wouldn't the multiplied quad-core (6.92 GHz) still get beat out by the multiplied duo-core (7.20 GHz)? Unless it still all comes back to the quad-core being able to multi-task better (due to 4 cores instead of 2) and run more programs at the same time? Does that even come into play during video conversion if you are using only one program?

[setarip_old]

@-Entropy-

Hi!

You may have to rethink your last post (in one or another direction because of either a typo several times or poor math):

3.06 x 2 (7.20 GHz)

[Blue_MiSfit]

Video encoders are typically nicely multi-threaded, meaning the single application can use all cores simultaneously. This is why a quad-core will be faster in cases like this!

It's also true that multitasking lots of single threaded applications will also benefit from a quad core.

~MiSfit

[-Entropy-]

Too true. Guess thats what happens when you post at 1am; or at least what happens when I post at 1 AM.

3.02x2 would be 6.12; not 7.20. Meaning it would rather be a 6.12 GHz (duo-core) compared to a 6.92 GHz (quad-core), "if" they did combine/multiply in that way. Math aside, that was really the heart of my question - trying to figure out if they do combine/multiply in that fashion. Is listed GHz per core or total?

[Blue_MiSfit]

Don't think about total GHz / GHz per core. That just leads to more confsion.

The chip runs at a certain clock speed - period.

If your app can fully use all 4 cores, then the app will run nearly twice as fast, compared to a similarly clocked dual core.

Now, with the Core i7, things get interesting :devil: - thanks to TurboBoost. This gem of an idea watches CPU usage, and when an app is hogging one core (but isn't coded to take advantage of multiple cores), the CPU can actually overclock that specific core, and slow the others down somewhat (to stay within the thermal envelope for the chip)! This means better single threaded performance! This is yet another reason why the i7 kicks so much butt!

~MiSfit

[LoRd_MuldeR]

...the CPU can actually overclock that specific core, and slow the others down somewhat

It even puts the "unused" cores to sleep. If you don't enabled this special sleep mode in the BIOS, then TurboBoost won't work.

I read that some mainboard manufacturers have it disabled by default :rolleyes: