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reemas · Feb 6, 2004, 05:11 PM

what is the difference between single and dual cpu's? for example a g5 1.8 vs a dual g5 1.8?? and is each chip 1.8 ghz or is it 1.8ghz total?

if the difference is huge, then why does apple bother with the single chip? i'm just rying to find out out more on dual chips.

Lateralus · Feb 6, 2004, 05:46 PM

It is two 1.8GHz processors.

Dual processing can be something of greatness because certain applications can be written to send an equal amount of work to both processors, thus doubling your processing power. Of course, that is theoretical. In actuality, some applications will take almost full advantage of each CPU when they are working, some applications will barely touch the second processor. The advantage of dual processors is traditionally seen in media related tasks: audio, video, imagings... etc.

If you're a basic user you probably wont see much advantage to going dual.

And to answer your question as to why Apple doesn't go all dual: Two processors costs twice as much as one processor.

The Placid Casual · Feb 6, 2004, 06:57 PM

2 heads in CPU terms are rarely better than 1.5!

If you do really intensive stuff with multi-threaded apps, or like to have loads of apps open at one time, a dualie is for you. If not, I'm pretty sure most users would be happy with one CPU and not notice the difference...

I think it is fair to say that dualies appeared (again, for the first time since early PPC days) in Apples lineup because of Motorola.

Moto could just not supply enough high clocking chips... well chips over 500mhz.

Moto didn't sort itself out for over a year, and were stuck under 500mhz for a long, long time while Intel and AMD sped into the lead mhz wise.

To compensate for this, Apple shipped dual machines, hoping people would think that 500+500=1000. Which it did, kind of.

Except that it didn't in OS 9, as only Photoshop has multiprocessor support!

In short it was big ruse until OS X was released... buy which time it was all academic anyway as even with dual processors, Apple was left in the dust in terms of raw mhz.

Also, you need the system bandwidth to deal with dual chips. The G4 processor was starved on the MPX 100/133/166 FSB that the chip allowed for (again, gee thanks Moto), when you tried to get 2 sets of instructions through the same place... it was a huge system bottleneck, now thankfully sorted out by the 'uber' bandwidth of the IBM G5 machines. Either way, 2 CPUs are very cool and have major Geek points, but don't equate to 2 times the CPU power.

It was painful, and I still have issues because of it!

Peace,

Marc

P.S. As PowerMacMan syas, it also costs Apple for 2 chips per machine thus meaning that prices will be high, making the dualie scenario just not practical for the whole range.

I Me Mine · Feb 6, 2004, 07:03 PM

Why is the 1.6 G5 generally frowned upon so much? Yes, there are less memory slots and no pci-x but surely an 800 FSB would help provide some nifty performance for the price?

The Placid Casual · Feb 6, 2004, 07:20 PM

Originally posted by I Me Mine:
Why is the 1.6 G5 generally frowned upon so much? Yes, there are less memory slots and no pci-x but surely an 800 FSB would help provide some nifty performance for the price?

Yep, it does. I think people just rag on it because it is a bad deal compared to the other 2 machines on offer price wise...

Less RAM, less speed, no PCI-X, etc etc But not that much difference in price.

In reality it is a great machine!

I think there is a kind of 'runt of the litter' syndrome going on, where people just pick on it because it is the lowest spec of the machines on offer, and it is the trendy thing to do...

In the light of day, compared to 2 dualies, it could be priced much more appealingly, and does look a little weedy.

But, put it another way, most Athlon XP users would love to have a 800mhz FSB.

Kenneth · Feb 7, 2004, 06:00 AM

I have been using my DP 1.25Ghz G4 (FW800) almost a year now. I am impressed with the performance although the G5 is here.

I will never go back to buy a single processor machine.. unless it is a PowerBook G5 (on my wish-list).

I run 2 SETI units almost 24/7 unless I am doing some video encoding, it is a great deal for getting a dual processors Mac.

FlatLyna · Feb 9, 2004, 11:08 AM

^^ What Kenneth said...

tooki · Feb 9, 2004, 12:01 PM

I say dual processors rock, for 2 basic reasons:

-Dual-processor machines stay much more responsive under load than single-processor machines.

-Dual-processor machines have significantly longer usable lifetimes. Owners of early dual-processor G4s are still happily humming along under OS X, which is quite snappy on those models. Owners of the single-processor units have mostly replaced their computers since then.

tooki

gururafiki · Feb 9, 2004, 01:33 PM

And to answer your question as to why Apple doesn't go all dual: Two processors costs twice as much as one processor.

[/B]

hehe. So true.

blakespot · Feb 9, 2004, 03:58 PM

I have a 2.5 year old dual G4 800 (Quicksilver) and I currently am not in the _least_ wanting for speed. I would have outgrown a single CPU G4 at that clockspeed long ago. With many apps running, the general ability of a dual system to handle load from many different apps is superb. The overall throughput is great.

blakespot

CIA · Feb 9, 2004, 04:11 PM

I wish my computer desk was that clean....
I second that. I have a Dual 800 QS machine, works great. Although the more I play with my dad's dual 1.8 G5 the more I question that....
Single Vs. Dual? Dual all the way regardless of Mhz.

djohnson · Feb 9, 2004, 04:36 PM

Originally posted by tooki:
Owners of the single-processor units have mostly replaced their computers since then.

I wouldnt exactly say that... I am running OS X on a beige G3...

Lateralus · Feb 9, 2004, 04:49 PM

Originally posted by djohnson:
I wouldnt exactly say that... I am running OS X on a beige G3...

Haha!

P · Feb 10, 2004, 05:24 AM

Originally posted by PowerMacMan:
And to answer your question as to why Apple doesn't go all dual: Two processors costs twice as much as one processor.

But the G5 CPU is cheaper than G4s, while the supporting chips are more expensive, so there is certainly room for a dual at the lower end Powermac. This is also the reason a really low end G5 is unlikely for now - the base chipset cost is too high.

Luca Rescigno · Feb 10, 2004, 06:29 AM

Duals certainly aren't faster than singles "at any speed." However, they do give you a modest performance increase. I could run two SETI units at once, but instead I choose to just run one. That way, I always have one processor open to handle whatever I'm in the process of doing, while the other can focus on SETI. If I put a heavy load on the computer, SETI will automatically throttle back and let other processes take over.

Also, iTunes ripping is a respectable 10-14x. That's pretty good considering each processor in my computer is only 450 MHz.

Given the light load I normally put on my machine, I really don't need a processor upgrade. However, if I were to get one, I'd still go single processor. They are simply cheaper than dual processor upgrades, and if I were to get a 1 GHz or greater G4 single processor, it would definitely overshadow my dual 450 in performance. Still, because of the versatility of dualies, I have considered a dual upgrade (if/when I want/need one). They are expensive but maybe by the time I want one they will have dropped in price.

Zoom · Feb 10, 2004, 08:37 AM

I'm planning to go dualie this time around. I've been getting by with a highly-upgraded G4/400 for four years now, and I'm ready to step up and try out a dual-CPU machine. I just hope the next rev has dual CPUs across the board so I don't have to fork over as much money to buy in.

Luca Rescigno · Feb 10, 2004, 10:46 AM

Zoom, if you want to see how a dualie would compare to your current machine, you could try getting a dual processor card from a Gigabit Ethernet (450 or 500 MHz) and putting it in your Sawtooth. It should work fine. That would be a pretty inexpensive upgrade if you can find someone willing to sell their dual G4 processor card.

OreoCookie · Feb 10, 2004, 07:37 PM

Although in a single app, Duals are usually not that much faster, thanx to multitasking, the other CPU can be used for other stuff, e. g. another app or for Quartz Extreme.

I also believe that Apple will put efforts into optimizing its software for several CPUs as most technologies are going that way. HyperThreading (to put it in easy terms: make software believe that one physical CPU is a dual CPU), cell CPUs, etc.

Other than the money for the second CPU, it doesn't cost Apple anything. In the PC world, you have to pay a hefty premium for Dual CPU equipment (mobo, RAM). Apple uses the same mobo for the 1.8 single and 1.8 dual. Ok, the 1.6 is another Yikes.

So I personally think it is worth it.