New G4 Memory Bandwidth Tests
xlr8yourmac.com posted the results of some in-depth memory bandwidth tests of the new G4 7450 rev 2.1 versus the older rev 2.0 units. Does this new chip revision offer notable bandwidth improvements over the rev 2.0?
Andrew's 2.1 rev 7450 showed more than 100MB/sec higher GaugePro memory test rates than a 2.0 rev CPU, but still not that impressive when compared to results from 7400/7410 G4s - even my G4/400 Powerbook (100mhz bus) had rates near the 867mhz (133mhz bus) rev 2.1 system.
Wow. Certainly the perceived advantage of the new G4's is not what one might first imagine, given other architectural bottlenecks (memory, hard drives, system buses, etc.) that come to bear on overall system throughput--but it definitely makes one want a rev 2.1 in their Mac! It would seem that this increased bandwidth might approach the performance increase that the inclusion of DDR memory would have offered--a feature whose absence has been much lamented on the message boards since MWNY.
It appears that some QuickSilver units are shipping with the 2.0 G4's and some with 2.1. Pretty much a crap shoot. So, if you've got one on order, keep your fingers crossed--nothing wrong with a little more bandwidth...
UPDATE: xlr8's added additional STREAM benchmarks, some of which show an almost 200MB/sec performance advantage on the side of the v2.1 G4's on some operations. Effect on video throughput is also covered (basically no effect).