What does this do? It breaks me computer :(

[CaterpillarAssassin]

BIOS setting that says, "100/133 Spread Spectrum" What does it do? When I enable it windows refuses to load. Please explain, thanks!

[waytoomuchcoffee]

It is designed to reduce EM interference by modulating the clock timer. However, it can really mess up stuff that needs discrete timing, like SCSI devices, or anything sensitive.

[FlyingPenguin]

Here's a little more background.

In simple terms, it forces the mobo to vary the clock frequency all the time. So instead of the front side bus being EXACTLY 133 Mhz, it'll vary between maybe 125 and 136 (as an example - I'm not really sure of the exact values).

What this does is spread the radio interference produced by the motherboard across a larger part of the radio spectrum which will reduce the overall interference (instead of a big radio signal spike it spreads out at a lower signal level). In many cases, this setting is necessary for a motherboard to pass FCC approval for RFI (radio frequency interference).

The problem is, this setting makes your computer inherently unstable - especially if you overclock or use high performance timing settings in BIOS.

I recommend disabling this feature unless you have a situation where a computer is generating too much radio interference (I used to have this problem in my old job where we had several computers crammed into a TV production trailer and sometimes we'd see radio interference from the computer get into some of the broadcast equipment. If you enable this setting, you should use the default BIOS settings to maintain a stable system.

[CaterpillarAssassin]

Thanks guys. Really explained it well

[Scooter]

Ask and ye shall recieve. I've always wondered that too..

[FlyingPenguin]

Here's a site with explanations of most BIOS settings: http://www.ping.be/bios/HTML1/settings.html