Changing the CPU multiplier vs changing FSB speed.

[Capitalizt]

For example, on an e6600 running at 2.4ghz with a 9X multiplier.

Your FSB would be set at 266 by default (266 x 9 = 2.4ghz), so in order to achieve a 3ghz overclock, you would change the FSB to 333.

333 * 9 = 2.997ghz processor speed.

Or you could change the multiplier to 6X, then the FSB to 500. 6 X 500 = 3ghz.

You get the same result from both methods..so which one is better?

I have DDR2 800mhz Ram, and am trying to figure out the proper FSB/multiplier settings for the most efficient (and cool) 3ghz overclock...

Please help a newbie out.

 

[SerpentRoyal]

Higher FSB will place more stress and heat on the MB and RAM. There's a small improvement in performance with higher FSB. CPU speed is still KING. Use the 9x multi and crank up the FSB until you reach the limit of the CPU at a given Vcore. Then bump up RAM speed using the memory divider.

 

[lousydood]

Well, frankly, a 3GHz OC isn't going to cause thermal issues. My temps barely budge when I go to 3GHz (same setup). I would put the FSB at 333 with a 9x multiplier so that you can leave SpeedStep enabled safely. I could be wrong, but, I think SpeedStep will reset your multiplier to 9x when it ramps up regardless of what you set it in the BIOS. You would have to disable it to fiddle with the multiplier.

 

[Capitalizt]

Thanks alot guys...I was about ready to go for a 3.2 overclock, changing the multiplier to 4X with an 800mhz FSB (to match my RAM speed 1:1).

It seemed logical, but I take it that's not a good idea?

 

[f4phantom2500]

Originally posted by: Capitalizt
Thanks alot guys...I was about ready to go for a 3.2 overclock, changing the multiplier to 4X with an 800mhz FSB (to match my RAM speed 1:1).

It seemed logical, but I take it that's not a good idea?

UHH...that's a HORRIBLE IDEA. I don't think your motherboard will even let you do that. DDR2-800 RAM actually runs at 400MHz, buddy. Your system's stock fsb is 266, and even with a 1333 FSB chip it would be 333 (assuming your board would support that). But in any case, basically what I'm getting at is that there's NO WAY your motherboard could handle an FSB that high. And then your RAM would be 1600MHz, which would also be impossible. Just set it at 8 x 400MHz, I think that's what you were going for.

 

[Ika]

CPU FSBs are usually pretty hard to get above 500mhz, anyway.

 

[ToXiCRaGE]

If you can change the multiplier then go for it, however, all CPUs these days are locked so FSB is the only way to do anything. If you have an unlocked CPU, changing the multiplier is the better way of the two.

 

[f4phantom2500]

Originally posted by: ToXiCRaGE
If you can change the multiplier then go for it, however, all CPUs these days are locked so FSB is the only way to do anything. If you have an unlocked CPU, changing the multiplier is the better way of the two.

Yes. Changing the multi is much more efficient in terms of giving you higher performance with less chance of instability. Since changing the FSB overclocks pretty much the entire system and changing the multi only overclocks the processor, and since the extra performance you'd see from upping the FSB would be negligible at best, then overclocking only the processor is the most efficient way to overclock, as it would be the only thing that would be instable (if anything), so it not only gives you less of a chance of hitting some instability, it also makes it very easy to figure out what's wrong lol.

 

[3Ball]

Set your memory to a 1:1 divider and drop the multi to 8x and then run your FSB @ 400mhz you will have 3.2ghz and your memory will run at its rated speed. These are settings I have for my 6420 and they are great. Hope this helps!

Best,

3Ball

 

[Capitalizt]

Originally posted by: 3Ball
Set your memory to a 1:1 divider and drop the multi to 8x and then run your FSB @ 400mhz you will have 3.2ghz and your memory will run at its rated speed. These are settings I have for my 6420 and they are great. Hope this helps!

Best,

3Ball

Thats exactly what I wanted to know...THANK YOU!

The multiplier maxes out at 9, but I am able to drop it at least on my Asus P5B...so I will probably go with that. OC'ing the RAM seems way too complicated to me, so I won't even go there until Quake 5 comes out

 

[PCTC2]

By the way, the lowest multiplier achievable on a Core2 is 6x. 4x is not an option.

 

[drakore]

phhh my C2D's have a 1x multiplier PCTC2.... i am running my e4300 @ 1x2900 FTW :Q