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http://www.insanely-great.com/news.php?id=806
1 GHz Face Off: Barefeats tests show the expected
By Michael Flaminio, Insanely Great Mac
August 15th 2002
As noted in a earlier article, Barefeats has measured up the new 1 GHz G4 against the
recent top dog 1 GHz G4. The results shouldn''t be all too surprising.
As noted in a earlier article, Barefeats has measured up the new 1 GHz G4 against the
recent top dog 1 GHz G4. The results shouldn''t be all too surprising.
Apple''s new PowerMac G4 towers feature a new system bus and the introduction of
faster DDR memory. The main system bus runs at 167 MHz, up from 133 MHz. This is
essentially how fast data can move across the bus. Everything plugs into this bus to
transfer data between components. For example, when a program loads, it reads from the
hard drive into memory which then is accessed by the CPU for execution. I guess you
can think of it as a mall parking lot, where shoppers drive from store to store. A
Bigger lot means more cars can move faster between stores.
The two G4 processors are connected via a slower pipe, or front side bus (FSB), than
the main system bus, which is believed to max out at 1.3 GB/sec, similar to the older
G4 systems. The main system bus can handle up to 2.7 GB/sec. It''s pretty obvious we
have a potential bottleneck to the CPU. This is due largely to limitations of the
current the G4 processors, which from all accounts appear to be PPC 7455 chips in
these systems, the same used in the last round of PowerMacs.
It appears all of the Barefeats tests are all pretty CPU intensive and the results
found shouldn''t be too surprising. The test machines are both 1 GHz machines so they
should score similarly on CPU intensive tasks. What this does show very clearly is
that we''re not seeing any improvement in CPU-like tasks due to the new bus and memory
architecture. This is kind of a bummer as most of us were hoping for a boost beyond
CPU performance. Why is performance the same? Either the pipe to the CPU is saturated
or there''s no real CPU speed benefit from the new architecture. Odds are its the
later, otherwise when the 1.25 GHz machines ship they too would run at the same speed
as the 1 GHz machines. We can wait and see, but I highly doubt this will be the case.
On the other hand we should expect some modest improvements in speed across the system
bus. This is basically operations that are more dependent on other functions such as
graphics, hard drives, FireWire or Ethernet than the CPU. For example, in test results
I''m seeing, there''s anywhere from 10% to 30% improvement in hard drive test
performance.
What does this mean to Mac users? This may put the squash on the latest round of
upgrades. Without any hefty boost in performance from the new memory and bus
architecture, we''re only left with a modest increase in CPU speeds. Perhaps that
clearance dual GHz G4 system might look a little better with its 4 MB of cache and a
$1100 lower price tag.
More tests, however, are needed to test performance beyond the CPU before the new
models are labeled a lemon.
Post your comments at:
http://www.insanely-great.com/news.php?id=806
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