Originally posted by: Eureka
Originally posted by: Sylvanas
1. The NB is perhaps the most important frequency on a Phenom CPU- almost more so than the Core speed. NB frequency reduces L3 cache latency and is especially important in memory bandwidth dependent scenarios.
2. NB can be manipulated by multipliers and it is generally easier to do it this way rather than HTT (it's called HTT not FSB) as you increase too many variables that way so it can be hard to determine what may be causing instability if it should occur.
3. Stock NB VID on a 955 is 1.1v. Make sure you are adjusting the NB VID or some BIOS's call it 'CPU-NB Voltage' and NOT the 'NB' voltage on the motherboard, this affects the 790FX chip and has nothing to do with the NB on the CPU (two different things, can get mixed up easily).
4. Most 955's get to 2.2ghz on 1.1v, you will need 1.2v-1.3v to get to around 2.6ghz. Load temps are the important thing.
Thanks for all the replies.
Sylvanas hit the nail on the head, I've been using 'NB VID' instead of 'CPU-NB VID'. Last night I was able to boot successfully with a 2.4ghz NB speed, but I didn't have time to actually try it out. I'll start playing with the settings after work.
Is there a benefit to raising the HTT speed rather than upping the NB mutliplier? Also, on my system the HTT clock is set to be a multiple of the "FSB" setting, what is the significance of this?
I'm also going to try to reseat the heatsink this time, I've had issues before with the S1283 being offcenter. Either that or I need to redo the TIM.
Glad to see it worked, I made the same mistake when I first got my 955- I was adjusting the wrong voltage. HTT is what programs like CPU-Z call the 'FSB' which is just for convenience sake as it's not really a Front Side Bus as per what Intel have been using for all these years- it's very different. So essentially FSB=HTT, same thing it's just what the software calls it. Why I say that adjusting the multipliers is better than HTT for overclocking is because with the multipliers you have may more control. With the HTT it comes stock at 200mhz, now for arguments sake let's say we up that to 230mhz. So now we have:
230 x 16 = 3680mhz Core Speed
230 x 10 = 2.3GHZ NB speed
230 x 10 = 2.3ghz HT frequency
2 (230 x 2) = 920mhz Memory frequency with the stock 1:2 divider.
That's 4 settings that have all been increased with the HTT. Now if something goes wrong, and we get instability- it could be any one of those settings that is the problem but we wouldn't know which one unless we changed the multipliers on each one and test individually which can take ages and even then, your results are not really indicative as a multiplier will reduce said frequency by 230mhz, which may be more than is required. So you are losing potential performance if you only need to drop down in reality by 10mhz for stability. Instead I propose adjusting each multiplier individually so what you'd end up with is something like this at stock and a little bump on the
core speed only:
200 x 18 = 3600mhz Core speed
200 x 10 = 2ghz NB
200 x 10 = 2GHZ HT
2 (200x2) = 800mhz memory @ 1:2 divider.
So if anything is unstable you know
for sure instantly that it is the Core that is unstable at that speed so you need only adjust that or apply a little more Vcore. So you can do this for CPU, NB, Memory and HT individually which will give you better results and the facts quicker than if you were to do it by HTT. Once you have the facts, you can tweak it later with perhaps a few mhz on the HTT.
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