[linux-audio-user] CPU clock - beware

Ryan Underwood nemesis-lists at icequake.net
Sat Jul 24 12:46:15 EDT 2004

On Sat, Jul 24, 2004 at 11:33:07AM -0400, Matthew Barber wrote:
> generally wants to run at about 33Mhz (unless you have a very new board
> with PCI-X or some such), and AGP at 66Mhz, and these values will
> generally be a fraction of the fsb.  So if your fsb is 66Mhz, PCI will
> be 1/2FSB.  If it's 100Mhz, PCI will be 1/3.  Setting it to 75Mhz may
> cause it to still be in the 66Mhz realm as far as the division is
> concerned, and set PCI to around 38Mhz, which may cause a lot of
> problems.

Yes, one thing this used to do was to cause data corruption on certain
Maxtor hard drives, at least under windows.  I think in linux, you can
pass a idebus= option to the kernel to tell it that the bus is

> I know some BIOS will take care of this by locking AGP and
> PCI to a certain value, but I wouldn't count on it with an older
> board/bios.

Also, even when the PCI bus is run asynchronously, while the data
corruption issues aren't around anymore, there is unfortunately a
latency tradeoff, which may make using a 75MHz/83MHz FSB not even worth
it in the end.

Ryan Underwood, <nemesis at icequake.net>
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