Voltage Meanings and How much do you really need - Overclock.net

cloudd901 · 02-16-07

I'm alittle new to Serious overclocking. I've done it on older boards running a P2 and such, but now I have a new Commando Mobo by Asus. This board gives me many voltage options that I can really use some help with.
First off I can use some insite to the Vcore voltage. I understand that this is for the cpu, but how much do you need?

I am running a P4 3.0, the original setting was 1.13v. I upped the processor to 3.25 by increasing 200Mhz to 215Mhz (I know it's not much, but I'm just doing tests for right now.) I tried using 1.3v (approx. 40*C) and it ran fine, now I have it at 1.04v (approx 38*C) and it runs exactly the same. My Bios reports this range as being low. Would upping the voltage really make a difference?

Once I can get this answer settled, I need to ask about some other voltage settings: SB vcore, NB vcore, SB sata and pcie, FSB Termination, and DDRII Termination.

xxpinoyxx · 02-16-07

welcome to the forums

will you please fill out your system specs through the user cp up on top of the site.

as for vcore, its best to use a little as possible while maintaining stability. up your fsb (or however you increase your cpu speed) as much as possible (by 5mhz increments) until you cant boot. once you cant boot, up the vcore just one notch from the default setting. do this until your temps get out of hand. be sure to watch your temps all the time.

cloudd901 · 02-16-07

OK, I got my system specs up.

Thanks for the info on the VCore settings. (As little as possible) Now what about the NB and SB Vcore Settings? Do I need to change these as I change my CPU voltage? Or adjust these completely separate? What are the benefits of these voltages?

xxpinoyxx · 02-16-07

sb vcore you should leave at its default setting. but nb vcore is what you should change if your having stability problems. its kinda like trial and error. you must play with different settings.

example:
if your nb vcore is 1.35v, and your cpu is at 1.45v. when you run a stress program and fails, you raise your vcore up a notch. so you try to stress it again, but it still fails, you raise the vcore once more. but once you stress it again and it fails, raise your nb voltage and see how that affects the stressing. if your able to stress w/o error, drop your vcore little by little until its as low as possible but maintaining its stability.

cloudd901 · 02-17-07

Thanks for the info, I just got done learning about my PCIE Frequency and trying to get the best out of my 3DMark06 test. I'm about to start testing out my CPU limits and voltage settings. What do you think the limits of a P4 3.0 are?

Ok, now what about the Termination voltages for FSB and DDRII?
I have my DDRII voltage at 2.02, and my FSB is running about 860, but I have no Idea what the Termination voltages are for.

**edit1** Just wanted to add the question, "Will more voltage (to any area) increase performance?"

**edit2** I found this post on extreme systems forums. This explaines the FSB Termination, but is it accurate to say that it is the same for DDRII Termination voltage? ---

Quote:

source -> line -> component -> short line -> termination

the "lines" in this case are signal traces. works a lot like a SCSI bus. high speed switching operations can cause reflections on the line (in essence, this is resonant noise caused from high-speed switching on the lines as the memory controller gates on and off to place data on the bus, nothing more than rising and falling voltages). clearly enough, the faster the signal switches (higher frequency memory) the more noise.

termination resistors, used in passive termination environments, are exactly matched to the target frequency for operation based largely on trace length, ESR (equivalent series resistance) and the over capactive/inductive nature of the circuit, as well as some other things well out of the scope of this post. problem is that this is often matched for a specific frequency...which as we know is not so cool for overclockers. enter the active termination system. this actually uses a voltage bias to set final line resistance value so that the user can tune for better operation when overclocking.

this method of tuning is largely trial and error as you have no way of know the specification of the circuit or have any idea of the calculations need to find the "perfect" value. so anway, the answer is, strangely enough, whatever works best.

**edit3** Got new question. What about DDRII Ref voltage? How does this affect the system and is it safe to play with?
Also, is 45*C idle and 61*C loaded a good system temp? Will it decrease the life of my hardware?

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Voltage Meanings and How much do you really need

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