FSB and machine speed

lphchild

This is a thick question I reckon, but is annoying me as a 'gap of ignorance'


My machine is runnng a 2.2GHz PIV at 22 x 100Mhz - the motherboard supports 133mhz, what's the difference if I run it at 16.5 x 133Mhz? - Is the machine actually runnig faster?

Cheers,

stoopid

Slutmonkey57b

The FSB determines the speed at which the processor interacts with the rest of the system (primarily the memory) so yes it does affect the speed quite a bit - also memory bandwith which is just as important.
Your P4 is speed locked to a certain multiplier - in this case 22x (100). Because the P4 does a trick called "quad pumping" it gets more speed out of the FSB then it should. If your memory runs at 133mhz (DDR 266 is "double-pumped" 133Mhz ram) you could try switching the BIOS to 133 Mhz FSB but I wouldn't recommend it.

po0k

Since multiplier-locked cpus have become the norm the only reasonable method of overclocking has been to increase the FSB speed.

Try it at 133 (with the lower multiplier as you said) and see if it runs.
Just try and make sure that your PCi divider is set to one quarter (133/4=33Mhz) and your AGP divier is set to one half (133/2 = 66Mhz) for stability.

lphchild

For stabilities sake I should leave as is then? - Cheers for the replies.. think I know what the story is now..

It's a TH7II-Raid, with PC800 Rambus and a 2.2 PIV - I think I 'll stick to the 22 x 100 :-)