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Methodology of test:
AMD-platform (1/2)
The tests on the AMD platform caused us most trouble. We had huge difficulties
to find a platform able to work at a 200MHz FSB. We didn't want to work
with a desynchronised bus, because we consider that this wouldn't bring
any performance increase on the AMD platform. That's why we were forced
to focus our tests on the synchronized FSB at 200MHz frequency. To make
our tests correspond as close as possible to the real operational conditions,
and especially to avoid minor differences between one CPU version compared
with another, we also did our tests with different CPU models and not
only the Athlon XP but also the Duron Morgan.
Unfortunately we where immediately confronted to a first problem. No
CPU accepted to be overclocked over 50% from its factory FSB values. This
made it difficult to go from 133MHz to 200MHz, and totally out of the
question in the case of a Duron to go from 100MHz to 200MHz FSB. The only
possible solution would be to modify the multiplication coefficient of
the CPU. On a Duron this intervention, which consist of unlocking the
multiplication coefficient, is very easy to realize and can be done in
a few minutes, but the Athlon XP does not allow such intervention. After
a few attempts to unlock some CPU models we finally decided to abandon,
because of an extremely unstable and unreliable operation. Based upon
this experience we limited ourselves voluntary to the CPUs, which have
the feature of unlocking the multiplication coefficient. Therefore we
limited ourselves to the Athlon XP/MP. These CPUs, besides their ability
to be unlocked, offer also the possibility to run under SMP mode (Multiple
CPU). And as we only wanted the best material to proceed the test we used
the Athlon XP/MP 1900+, which is actually the fastest available. Let's
take a look at this CPU:
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On this CPU the official frequency is obtained with a multiplication coefficient of 12 and an FSB at 133MHz. This allows us to reduce the multiplication coefficient to 8 and run a 200MHz FSB… That's just what we did.
Once the CPU problem resolved we had to source the right motherboard.
Of course it's not enough to have the CPU, you also need a motherboard
that has the ability to run this high-speed FSB. The main problem there
is the FSB/PCI ratio, which normally never exceeds 1/4. After checking
at different sources we were not able to find a motherboard offering a
1/5 ratio. So we had to choose an excellent 1/4-ratio motherboard, for
the test we have chosen the EPOX 8KHA+, which has proven excellent performance
and reliability in overclocking environment.
Once the CPU and motherboard part was solved we needed an excellent hard drive. For the best performance we have chosen the Seagate Barracuda III. The Barracuda IV refused to start with a PCI at 50MHz! ! ! For the Graphic card we needed one with an AGP at 100MHz instead of the generally used 66MHz. After testing different cards we have chosen the GeForce 3 Ti 200 from Prolink. Equipped with 128MB Graphical Memory this card is perfectly compliant with a 100MHz AGP.
And the most difficult had to come, we noticed in previous tests that the Epox 8KHA+ encountered some problems when the FSB exceeds 185MHz - 190MHz. After some research and additional tests we finally concluded that the cause of all this trouble could come from the chipset, and especially the NorthBridge. Even at the basic speed of 133MHz, the KT266A chipset was heating a little bit. But once you're increasing the FSB speeds close to 200MHz frequency the chipset could exceed a temperature of 60°C… It's easy to understand that under these circumstances even the standard cooler wasn't able anymore to dissipate all the heat. We decided to adopt a more powerful cooling system, specifically for this chipset.