FSB and Clock speed confusion

[eddyc]

Hi everyone,

I am very new to overclocking but having a lot of fun fiddling around in BIOS. I am using a M4A785TD-V Evo mb and a Phenom II X2 550 BE (unlocked to X3).

I have been trying to follow the beginners guide but getting stuck on the first bit. I do not have an option in BIOS to change FSB, although I can change an option called Clock Speed.

Is this the same thing as far as the mb goes? The guide seems to distinguish between them.

Also since I have a fully multiplier unlocked processor should I be balancing between overclocking using the multiplier and the FSB or just using one of them? Which is better?

I would really appreciate any help on this.

 

[ran_out]

That clock speed option should probably be the bus speed - it should be at 200 as default for that CPU.

I think to begin with at least you will probably get the best results quickly from making increases to the CPU multi and the CPU NB and seeing what if any voltage adjustments are required to run stable (personally I have stayed under 1.475v until I know a bit more about my CPU and it's limits and how well my cooling is working). If you find system to not be stable after increasing the multi, try increasing voltage by 0.0125/0.0250 and testing again. I dont how it will affect things having the unlocked core though, you may find that it does not clock as well with 3rd core unlocked, i really don't know - will probably depend on the chip.

Changing the bus clock will affect other bios ratios and from what I hear it's not as likely you will be able to make any major increases to this without running into other problems with stability. Not saying not to experiment, just that I have found best results from upping the multi, and only making minor adjustments to this.

I've only had an AMD CPU for a few days and am still messing about with mine, so can't tell you much. I have an x4 955 C3 running at 3.8 (205*18.5, CPU NB@ 2200mhz) but have had to raise the CPU voltage a little bit to get this stable. Not really looking to push it much further than that though, i'm going to look at reducing the OC and running at as high as i can at stock voltages.

 

[eddyc]

Thanks for replying ran out I will certainly start out with changing the multi, I did hear that having an unlocked multi made OCing much easier. Part of the reason why I bought a B.E. processor.

What effect does increasing the cpu nb frequency have? Is that RAM overclocking?

I am assuming that if a multiplier increase renders it unstable I should increase cpu voltage and if a nb frequency increase does it I should increase nb voltage. Is that right?

Thanks a lot for the advice.

 

[ran_out]

I'm fairly new to AMD CPU's so not sure i'm experienced enough to be giving much advice, but I believe the CPU NB is the CPU memory controller. It defaults at 2000mhz but can be run at hgher speeds without having to increase voltage by much if at all. I think you are right in saying that generally speaking increasing the core voltage for stability with higher multiplier and NB voltage for higher NB frequencies is correct.

NB voltage max is not necessarily the same as the core max I think though so check this out before making adjustments - I think between 1.2-1.3 is safe - but that is just based on info in another thread I read so wouldn't put trust in it without some confirmation.

 

[eddyc]

Thanks a lot for all the help.

Sadly I am separated from my rig for a few days so wont get a chance to try this out till sunday night probably.

Will have a play and see how it goes. Really want to try to get up to 4.1 ghz.