Originally Posted by JDW
The first two pages of comments were an absolutely amazement to me. Virtually all about BlueRay. Who the heck cares? (And I say this as someone who wants BlueRay.) All this BlueRay talk is irrelevant when it most assuredly will be a BTO option at some point. So let it go!
Personally I'd rather Apple get rid of the optical drive altogether on a MBP and give us three bays for at least 3 SSD drives. I'm very much of the sort that wants his movies carried internally. The problem is the extra effort to carry all those optical disks and keep them scratch free. Frankly Apples iTunes is good enough for that.
As for a TV in the house I gave up on that. Between cable costs and the price on DVDs it is cheaper to go the movies once a week.
Now if you want to talk about the real meat of this article, this comment is more spot on...
Now think deeply, people. Think. Do you honestly expect that a 1.7 or even a 2.0GHz 4-core CPU (even i7 based) could hold a candle to a 3.06GHz 2-core iMac in terms of "real world performance"?
The problem here is that performance on these processors will be all over the map. This due to a number of issues. But I think you are right in that a 2GHz processor will have a hard time competeing with the Core 2 processors running at 3GHz. That due to the Turbo Boost not always cranking up to max clock speed.
Many will argue that only one processor is used for for single threaded programs and that they will run just as well. Well it may or may not. The problem is a modern Mac is almost never running just one program. Plus you have GCD trying to do it's best to leverage all those cores, so it is not likely that the processor will have many opportunities to run in single core mode. This doesn't even discuss the temperature of the processor which is always a problem on Apple computers (no turbo boost when hot)
Lately I've been hearing that you might get 20% more performance clock for clock. That is very possible but it still doesn't hit the performance of the top of the line Core 2 processors. This is why I say things might actually suck if Turbo Boost can't kick in. What it comes down to is that it will depend and eclipsing todays iMacs is not a given.
If you do think that, you are deceived.
Well I think that might be a bit strong. The potential is there for good performance in certain situations. But I don't think people understand how modern computers work. First they may have many processes running at the same time even if they aren't user processes. Second programs use system resources which may be highly threaded. The idea that we are in a single threaded world just isn't true anymore. So how often will the processor actually be able to Turbo Boost. No body knows but in many cases single thread performance will suck.
As was the case with the very first PPC Macs that were slow because there wasn't enough "native" software out there for them, slow clocked 4-core CPUs will be hindered by the lack of multi-core software available for them. The end result is that a 4-core iMac -- at sub-2GHz clock speeds -- would certainly feel much slower than the current high-end iMac.
This isn't the case either. The problem is there are few programs that I would call hard single threaded programs anymore. Many common programs that users take advantage of are already threaded and more are every day. Even the lowly word processor is threaded these days. Many apps will run just fine on these processors. Combined with SL and the better multi processing behaviour of the i5 & i7 processors the performance may be very acceptable. But (it is a big one) hard single threaded portions of a program will suffer if the processor can't Turbo Boost.
Will people be disappointed with the new iMacs if they go this route(mobile processors)? I'm not sure because it will very much depend on each users load on the computer and software choices. Will it feel slower, well maybe, you might be uderestimating just how responsive the machine might feel with quad cores. GCD and other feature of SL really have had a significant impact on how my MBP fells. Until I see and work with one of these new machines, I'm not going to guess at performance or feel.
Don't get me wrong. I too want a quad-core iMac. My goodness do I want that. But I want it at a clock speed that rivals what we have now.
Well when you talk about clock speed this way I think you don't know what you are talking about. Todays processors do one hell of a lot more than the Core 2s of yesterday, clock for clock. The other problem is that intel simply doesn't have faster clock rate mobile processors right now.
It doesn't necessarily need to go as high as 3.06GHz (which may be impossible in terms of cooling in an iMac), but it certainly should be above 2.5GHz.
Well that would be nice but we will likely have to wait for 32nm processors for a good clock rate. Again that is if Apple goes with these new mobile processors. If they go the XEON route we might get closer. But right now +3.0 GHz is only going to be hit via Turbo Boost when it can kick in. But you are right in a sense to get the same performance at the chips base speed we will need a 2.5 GHz processor, otherwise you will have to rely on the variability in Turbo Boost. In any event we will have to watch carefully for thermal throttling on the new machines.
Again, think "real world" practical performance here people. With all this talk of low clock speeds, a dark cloud has come over what was an otherwise exciting time for me: the imminent release of new iMacs with "compelling new features."
Don't let the dark clouds in yet! We will know in the near future what will actually be in the machines. But yeah if the machines have the rumored mobile processors I wouldn't buy until I see some ethical testing. Apple however has choices and maybe they will make the right choice.
But for me, just how "compelling" those new iMacs will be will be locked to the clock speed (i.e., real world performance).
OK but realize clock rate isn't an indicator of real world performance relative to older machines. This idea that clock rate means anything relative to different generations of processors have to die. At best you can say that 2.5 GHz is the minimum you need to get similar performance to Core 2. Even then that has to be qualified by saying that it excludes Turbo Boost.
All in all I have to agree with the pessimism you display. If Apple goes the mobile processor route performance will be all over the map with more variables than most people are use to. Interesting times ahead.