If the clocking remains at a fixed frequency, the noise
generated also remains in a narrower band with more effect
on other devices susceptible to noise pickup in that band.
Spread spectrum varies that clock rate to minimize the
effect. Generally I always disable Spread Spectrum as I
never observe any problems on nearby equipment but if you
did that's one place to look at resolving it.
If the clocking remains at a fixed frequency, the noise
generated also remains in a narrower band with more effect
on other devices susceptible to noise pickup in that band.
Spread spectrum varies that clock rate to minimize the
effect. Generally I always disable Spread Spectrum as I
never observe any problems on nearby equipment but if you
did that's one place to look at resolving it.