Athlon 64 multiplier locked?

THE ATHLON 64 is one mysterious processor. I have been playing with this nice, 64-bit marchitectural delight for last few weeks and am still amazed by it.

What I used to like about Athlon CPUs was that they where almost always unlocked -- at least if you had a decent motherboard -- preferably one from Epox or Abit since they'd fight for your overclocking rights all the time.

Well, the Epox 8HDA+ motherboard based on VIA's K8T800 just got new a bios that even unlocks the multiplier on your CPU, as well as the voltages of your CPU, memory and AGP. The FSB unlocks too, of course. The new bios includes suggested multiplier settings, but if you move these from 10 to 11 on an Athlon 64 chip, nothing happens.

Surprise, surprise: if you set the multiplier to 9, the board actually underclocks your 2000MHz clock CPU to 9 times 215MHz resulting in 1944MHz.

We confirmed this with the Clock Generator application developed by our friend Frank from www.cpuid.com, with yours-truly as the only beta tester of its RTM360-802 application. With this, you can overclock and change everything from Windows while the Epox board will let you do this from your Bios.

But no matter how you overclock or underclock your Athlon 64, the Epox board will always report that you have an Athlon 64 3200+ CPU and won't tell you the real CPU frequency.

As far as we could tell, the Athlon 64 multiplier is locked to upstairs steps but you are more than welcome to downclock your CPU and then compensate with the FSB, should you feel the urge.

Observations welcome. µ