More FSB, Less Overclocking?

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The Inquirer reports that this AOpen page hints that AMD is going to increase the FSB on Hammer mobos sooner rather than later.

XBit Labs more or less reiterates the thought when talking about future SiS chipsets.

If you follow through the links on the XBit Labs article, you come to this piece, which shows the specs for these future chipsets, including memory.

There’s no DDR2 there. Just DDR400.

This tends to confirm what we said the other day about AMD not going to DDR2 until late 2005.

Should this be true, there’s a financial plus and a mixed technical bag.

Those of you who already have DDR400 or better could continue to use your RAM in a new system.

While a higher FSB won’t directly benefit a DDR400 setup, it could help indirect a bit by removing bottlenecks so the memory can be the best it can be (though this is likely to be of benefit only to dual-channel systems).

On the other hand, for raw potential memory bandwidth, Intel will get an advantage with its DDR2 platforms.

For overclockers, there’s an even bigger disadvantage.

More FSB, Less Overclocking?…

More FSB, Less Overclocking?

From what we’ve seen so far from the Hammer chipsets, a 250MHz FSB will greatly reduce the potential FSB overclockability of Hammer CPUs. It’s probably safe to say that the current maximum FSB sustainable by current chipsets (running with memory going slower than FSB) is probably around 300MHz (if it’s even that high).

Going from 200 to 250MHz FSB with such a chipset means the maximum potential overclock is reduced from 50% to 20% (300/200 vs. 300/250). A chipset would have to be able to reach 375MHz for a 250MHz FSB CPU to regain that 50% overclocking potential.

This is a major concern for the Athlon 64, with its locked multiplier. A bit less of a concern for the FX so long as it has an unlocked multiplier, but cost is the 800-pound gorilla there.

This move would effectively serve to make any serious degree of overclocking infeasible with the Athlon 64, and attempt to push overclockers towards the FX.

How bad that will be depends on what AMD plans on charging for FXs in the future. If A64s are made relatively unoverclockable (while remaining relatively expensive), and FXs continue to cost an arm and a leg, overclockers are going to have second thoughts about AMD.

AMD may well want to rid itself of cheapskate overclockers, but it ought to remember that a bird in the hand is worth two in the bush.


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