MacWorld's iMac Core Duo Benchmarks Debunked?

madgunde writes "Looks like MacWorld magazine was a little premature in reporting that the new Apple iMac Core Duo doesn't live up to Apple's speed claims. The folks over at MacSpeedZone have done some performance testing of their own that debunks MacWorld's results and shows that the new iMac Core Duo DOES live up to the hype. Not only did the new iMac wipe the floor with the old model in their tests, but using MacWorld's own test methodology would allow MacSpeedZone to conclude that the new Intel iMac is almost as fast as a PowerMac Quad G5. " I see only one way to solve this: Give me one. I'll run WoW on it, and decide.

Comments

Re:What was MacWorld's flawed logic?

[rjstanford]

Its referring to tests that don't max out the CPU anyway, and therefore presumably have bottlenecks in some other part of the system. Here's a more rediculous example using the same theory:

Test: Compressing and sending a 16MB file over the network
iMac: 83 seconds (cpu usage 23%)
quad: 84 seconds (cpu usage 11%)

Wow! The iMac is faster than the quad! Of course, in reality it was working much harder to accomplish the same task (compressing at a bandwidth-limited speed). The articles point - and it is very poorly written, I will agree - is that this kind of test is crap.

The Macworld test used the same theories in the other direction. After all, if you perform a task that takes the old G5 iMac 20 seconds but uses 99% of its CPU, and takes the new intel iMac 19 seconds but only uses 45% of its total CPU power, I think you'd say that the iMac was more than 5% more powerful, right?

Admittedly if all you ever do is one task at a time, you wouldn't notice the difference. Considering that many people like to do multiple tasks - watching the recent keynote in a background window while doing some other work in a foreground window, for example - this is not an inconsequential point.

That brings up the example from the linked MacSpeedZone article:

Encoding one QuickTime movie:
intel dual core iMac: 97.02 seconds (87% CPU)
g5 quad core powermac: 84.85 seconds (42% CPU)
advantage g5: 14% faster

Encoding two QuickTime movies:
intel dual core iMac: 176.60 seconds (100% CPU)
g5 quad core powermac: 86.25 seconds (87% CPU)
advantage g5: 105% faster

Even that's a little misleading, since the quad still had spare processor bandwidth. This is why a lot of benchmark tests are designed to test each piece separately, spinning them up to 100%. Of course, real world tests are great as well - but only if your usage actually parallels those tests.