so i OC'd my xp 1600+...

[Ktulu]

Its at 1.6mhz, and registers as an xp 2000+. It was at 1.6GHZ since it started registering as a 1800+. Is it just me or is that not right?

also, the bios has something called spread spectrum. ANy one know what this is? The mobo is a MSI k7t266 pro 2. The fsb atm is...150 if im not mistaken.

[Molester]

spread spectrum should be disabled

[Supertrucker]

i disable spread spectrum, i think its something about an allowed variance in fsb. and most mobos just guess a pr number based on clock speed.
1600+=1.4ghz
2000+=1.66ghz

[Ktulu]

ALrighty, im gona disable spread spectrum as soon as i finish this WU.

[TheGr8s1]

instaed of just telling him to turn spread specturm off why don't u explain why. what does specturm do in the first place? u didn't answer his question correctly and i'm curious myself.

[Tyranos]

turning spread spectrum off is used to make the signal wave spread shorter, and the clock frequency a bit more accurate and faster. This adds EMI (electro magnetic interference) though..

[c627627]

Originally posted by TheGr8s1
instaed of just telling him to turn spread specturm off why don't u explain why. what does specturm do in the first place? u didn't answer his question correctly and i'm curious myself.

...because after reading the following, the only thing an average person remembers is that it should be turned off :beer::

Originally posted by max0mus
Spread Sprectrum is a common technique used in wireless communications systems. It is used to "hide" a wireless signal. That is as simple as I can make it.

Now in the case of a PC, the FSB frequency being generated on the mobo radiates (emits) the FSB signal into the air and thus now polluting the air, so to speak. That "pollution" can seep into other components on the mobo thus "interfering" with it. Spread spectrum applied on the FSB signal essential reduces the amount of pollution seen eminating from the FSB signal generator.

How Spread spectrum works physically is by varying the frequency of the signal "randomly" so that the instantaneous frequency is always changing with time. ON AVERAGE, the perceived power coming from a Spread Spectrum signal is lower since it is only present at any one frequency some of the time.

NOW, you can see why disabling it is good since the FSB signal is now "constant" but then the drawback is that it causes more RFI (Radio Frequency Interference).

The percentages you see don't have alot of meaning in abosolute terms but you can gage their effects relatively.

[c627627]

Here's some more to choke on:

Source: AoA Forums


Spread Spectrum is a method for reducing the potential for EMI. As you probably know, PCs use various frequencies internally. Whenever you send frequencies down a wire, it acts as a radio transmitter! Admittedly, it's only a weak one, but with enough wires, and enough different frequencies, there's a good chance for local interferance. Things like radios, cordless phones and other devices can be affected by this interferance.

If you have a FSB, running at 133MHz, then the main frequency that will end up as RF will be 133MHz. If you profile the RF spectrum of such a system, you'd see a strong peak at 133MHz. If it's strong enough, then the item breaks various regulations, and hence isn't sellable. (Europe is quite keen on keeping RF leakage down! I don't know about other areas)

The spread spectrum setting is almost like a cheat to work around this. Instead of keeping the FSB at 133MHz, for one instant, the FSB runs at 134MHz, the next it runs at 133MHz, and the following it runs at 132MHz.

The average is 133MHz, agreed?

However, because it's only spent a 1/3 of the time at 133MHz, the RF peak is only a 1/3 of what it would be if the FSB was always at 133MHz. Hence, the average power at that frequency has dropped by 2/3, a pretty big reduction! This is generally enough to ensure that said devices pass through testing with flying colours.

In real life, spread spectrum uses far more than just 3 frequencies. It may use hundreds! This helps to keep the overall profile of the RF noise generated down. There's generally a percentage. This is the percentage deviation from the average clock frequency. If the percentage is 0.5%, then a 133MHz bus would actually vary from 133.665MHz down to 132.335MHz

The downside?

Items like the FSB are no longer running at one set frequency. If your machine locks up when the FSB hits 170MHz, and the spread spectrum range happens to hit that magic 170MHz, then your PC locks up. This may be despite the fact that the average FSB speed was 165MHz. Hence, the clock generator was generating frequencies from 160MHz up to 170Mhz. (Yes, it's an artificial example!)

If you can run spread spectrum without instability, then do so, please! It helps devices that rely on radio frequencies operate with less interferance. PCs are well known for causing a broad spectrum of RF "hash" that can interfere with many things.

Just a note: Square waves used in PCs don't produce just one frequency of RF interferance. A square wave is made up of many sine waves. Each of those sine waves causes it's own level of interferance! The fundimental (or strongest) sine wave is at the same frequency as the square wave. The next sine wave is 1/3 of the power, but at three times the frequency. The following sine wave is at 1/5 the power of the fundimental, but at five times the frequency!

Hence, your FSB running at, say, 170Mhz is causing interferance at 170MHz, 510MHz, 850MHz, 1.19GHz, 1.53GHz and so on!

bla...

[qwerty57]

this was my air cooled 1600+ back in the days :)
http://jason57.iwarp.com/ti460015.jpg