unlock to overclock?

[beverage]

Ok, so I've been doing some reading here in the last few weeks and I keep seeing people discuss "unlocking" their AMD chips in order to over clock them.

I have an XP 2100+ and an MSI K7T turbo2 motherboard. In my BIOS I can just up the FSB to as high as 166...

Am I missing something here?...Am I not supposed to just change the FSB in order to run my CPU faster?

 

[Confused]

With most chips, in order to increase FSB speed (which will make more of a difference than multiplier alone) you will need to reduce the multiplier, as CPU speed = FSB x Multiplier.

So, to get those high FSB speeds, you will more than likely need to unlock your processor and lower the multiplier


Confused

 

[beverage]

so if CPU speed = FSB x Multiplier...

by raising one, and lowering another...how exacly does this make the CPU run faster..

my current multiplier is 13
and FSB is 133

lowering the multipler to say...12 would mean i'd have to raise the FSB to 144 just to get back to where I started...

why lower one when it only means you'd have raise the other even more to compensate?

which is more important when overclocking...CPU speed itself, or the FSB? if it's FSB, then this makes sense,...I was under the impression however, that acheiving higer CPU speeds was the main goal...

 

[BigJ]

Originally posted by: beverage
so if CPU speed = FSB x Multiplier...

by raising one, and lowering another...how exacly does this make the CPU run faster..

my current multiplier is 13
and FSB is 133

lowering the multipler to say...12 would mean i'd have to raise the FSB to 144 just to get back to where I started...

why lower one when it only means you'd have raise the other even more to compensate?

which is more important when overclocking...CPU speed itself, or the FSB? if it's FSB, then this makes sense,...I was under the impression however, that acheiving higer CPU speeds was the main goal...

High FSB = Bitching performance
This is the reason why at stock speeds...a P4 running on a 533mhz FSB will beat a P4 running on a 400mhz fsb, or an Athlon XP 1600+ overclocked and running at a 166mhz FSB for 2100+ speeds will beat a stock Athlon XP 2100+ running on the 133mhz FSB. This is why some people will sacrifice pure speed in mhz for a high fsb (i.e. overclocking an Athlon XP with a 200mhz FSB and 8.5x multipier for 1700mhz vs. 166mhz FSB and a 10.5 multiplier for 1743mhz, the person will take the 200mhz FSB)

 

[randomboy]

Originally posted by: BigJ2078[/i
High FSB = Bitching performance

Thats a great summary right there But if you had 2 similarly clocked CPU's, one with a significantly higher FSB than the other, why is the performance that much better?

 

[railer]

Once you start running your FSB way out of spec, things can sometimes get squirrely and stop working. Things like PCI and AGP cards, and hard drives. Little things like that. I screwed up one of my HD's by running it at a 41 mhz FSB for a couple of months. Lost all of the data on it. That's why people unlock. Besides, you probably won't be stable running at 13x166, but you would be stable running at say, 10.5x166. (or 10, or 11, etc. that's the beauty of unlocking...you pick the best multiplier.)

 

[XBoxLPU]

Higher FSB on PIV's give better performance than higher FSB on AMD, because the AMD CPU is not starved for Bandwidth like the PIV CPU is on a DDR setup.

I am currently running 186 FSB @ 9.5 Multiplier on an unlocked XP 2000+ = 1.77ghz or 2200+. My memory scores in sandra are 2700/2500 about.

Higher FSB and lower multiplier are the only way to OC AMD CPUS

 

[Evc]

Originally posted by: XBoxLPU
I am currently running 186 FSB @ 9.5 Multiplier on an unlocked XP 2000+ = 1.77ghz or 2200+. My memory scores in sandra are 2700/2500 about.

Higher FSB and lower multiplier are the only way to OC AMD CPUS

Odd, I am running a lower FSB then you (182) and my Ram scores in Sandra are near 3000