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Phenom ii X4 NB Overclocking

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Porvalsh

Member
Joined
Aug 14, 2009
Location
Colorado
I've been working on overclocking the NB because it seems to be effecting my 3dMark scores the most. I read a post the other day with a guy showing he's overclocked his NB to just over 3100mhz... thats a lot. He was doing this for the 3DMark05 low clock challenge.

So I ventured to see what I could do. I cannot get above 2800mhz. Its frustrating, because the bios will not post and now that I've changed my case around, I cannot easily reach the Reset CMOS button on my motherboard, lol. This board resets automatically after 3 failed attempts but since it doesn't even get past FF, it doesn't know that its failed. So I have to do the old fashioned, pop the battery out and back in trick. Thats annoying.

What happens is the computer won't even post. It stays at "FF" blinking motherboard message and never goes beyond. FF is the start of the CPU boot cycle. Obviously something going on there that it doesn't like.

So, my best setting so far (and I didn't tweak too much yet) is 2800mhz CPU-NB with CPU at 3400mhz. Difference is 600mhz. CPU-NB running at 1.3v.

I tried many different configurations within these ranges:

CPU between 3400-3900mhz
CPU-NB between 2900-3000mhz
HT Link from 2000-2500mhz
CPU-NB volts 1.3-1.42
Slower RAM timings
Slower RAM speed 1333-1700

Then I got tired of popping the CMOS battery out so I stopped and went to bed. :) It could be that 2800mhz is all that my chip will do at those temps. I'm assuming that scaling of the CPU-NB is much the same as the CPU, like perhaps the CPU-NB cannot get above 2800mhz similar to how the CPU will not break 4ghz without being in the 20C range. Tonight I can do more testing to see if this is the case, as its pretty cold outside. 2800mhz is a 28.5% overclock, which similarly would put my CPU at 4112...something that I haven't achieved yet.


Please share any tips you've got for overclocking the CPU-NB.
 
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What are the temps like?
I don't really have much to say as i haven't done a lot fo cpu-nb overclocking, but i did notice that cpu-nb voltage makes a huge difference in cpu temp.
It wouldn't surprise me at all if it wanted to be cold to go fast, really.
 
The guy was cold that's for sure, the rule of thumb (at least mine!) is to try to keep the NB within 1.2g of the clock, going cold @ aroung 6.0g I run the NB @ around 4.6 to 4.8 (depending on the board, some go high some don't)
 
Temps were around 40C, but never really stress tested the CPU. I was going for 3000mhz, not really 2800...I'm water cooled, CPU only loop with a 120.3 and 120.2.

If I run 1.45-1.5V on the CPU and 1.35 on the CPU-NB I'm in the 44C range.

I could get it to run at 2800mhz though on 1.3V, with stock voltage on the CPU. This translated to much lower temps.

I'm thinking I'll need to be below 30C though to get my CPU-NB to 3000mhz, but it just seems weird that I can't even post at that speed right now. I wonder if the config is screwing things up. Feels like maybe the CPU-NB/CPU ratio is too close to 1:1 that the CPU is tripping over itself and can't even POST. Or maybe its too fast for the RAM and trips it up?

I dunno, but will test more tonight, and maybe post more organized results.

My best 3dmark scores are from roughly 3900/2800/2500, near 1700 DDR3.
 
The guy was cold that's for sure, the rule of thumb (at least mine!) is to try to keep the NB within 1.2g of the clock, going cold @ aroung 6.0g I run the NB @ around 4.6 to 4.8 (depending on the board, some go high some don't)


Hey Icebob, in your experience what kind of voltage do you need to run your CPU-NB at certain speeds. I've read similar people trying to keep their CPU-NB to CPU speeds about 1000-1200mhz apart but the problem I have is that when my clocks get high, I don't know which is the limiting factor, and therefore am unsure to pump volts into the CPU or CPU-NB.

In order to try and test this I've been leaving my CPU between 3200 and 3500, speeds at which I know I can run stable with Auto volts. As the CPU-NB gets up there though, it begins to shrink the difference between the two. Therefore, I do not know if the speed difference is holding me up, or the voltage, or the heat limitation.

I think in Dolk's guide, he mentions to not go beyond 1.3v on the CPU-NB.
 
Do you have a fan on your NB? Good idea to put one there. For the kind of oc you do, you can probably go a bit pass 1.3v(on the NB) and probably close to 1.5 on the cpu. Watch your temps and go little step at a time, since everyboard is different (never tried GD70) only trial and error will tell. And at that low oc (3.5/3.6) you don't really need to get your NB really high, just a notch or 2 should do the trick
 
You might try downclocking the CPU to 3.2 and seeing if the CPU-NB is willing to run at high(er) speeds.
There may be a communication issue, considering that they're used to talking across a 50% (roughly, 2ghz to 3.2ghz) speed gap.

EDIT:
A fan on the mobo-NB is certainly not a bad idea, that is what the CPU-NB talks to after all, and it may get overclocked somewhat when having to talk to a higher clocked cpu-nb (no clue, but seems possible).
 
I'll get a fan going and see if that helps. Since the comp doesn't even boot, I have a feeling its not even getting hot.

I'll mess around with higher FSB settings too...who knows, maybe my board doesn't like the higher multi for the CPU-NB.

Tonight I can run some tests outside since it will be colder, and see if temp is the issue too.

I already know I can run my CPU-NB at a lower sweetspot when the CPU is in the 3600 range but I'm trying to find out if there is a better sweetspot higher up that its capable of and maybe find a better configuration for gaming than just straight processing power.
 
icebob needs a fan on the chipset, those DFI boards tend to run hot.

I have only run a couple of the 790 boards, and not one has gotten hot for me (VRM/FET's yes... not chipset though)

CPUNB speed seems to effect chiptemps more so than than vcore, it might be a good idea to check your FETS and see if they are running hot supplying that much current.
 
Well unfortunately, I don't have an IR heatgun. Should I be able to hold my fingers on them as long as I wish?

Thanks for all the replies guys, lots to do tonight.
 
Oh yes.
If they feel hot, they're hot.
Ideally they'll be warm to very warm. If you can't hold your fingers on it, it should have a fan.
 
You can only achieve a 3.0ghz CPU-NB why having a 4.0ghz CPU Frequency. Trying otherwise is futile, something I've done extensively.
 
Interesting, so there is a minimum gap between CPU and CPU-NB speeds?
 
Something like that. In my experiance it seems that way, which makes sense. If you have an internal part of anything going to fast than the other internal parts, errors will occur. Whether this is something written into the chip itself or just coincidence, the CPU cannot exceed 3ghz on CPU-NB without the CPU Frequency being high enough.

I wouldn't be surprised if you could do it with 3.9ghz though.
 
Very interesting Dolk. I had wondered about that before, but I figured it does not exist, since I am currently running 900 MHz CPU speed and ~2400 MHz CPUNB speed lol
 
Did some testing last night. My conclusions are that the NB frequency does not have to maintain a certain mhz difference from the CPU frequency. They will not "trip" on each other or anything like that. I will post more detailed results later. I've got some school stuff to do right now.

About the 2800+ mhz CPU-NB not posting issue. I found that when my CPU is running between 20-30C, this ceiling is raised. From my testing, I've concluded that there is a CPU-NB heat barrier, much like what Dolk talks about in his "4ghz Range" section of his Pii guide. Once I attained temps below 30C, my computer was able to run with CPU-NB higher than 2800mhz. Similarly, at these temps I can run in the 4ghz range.

I tested settings @3800 CPU for 3000mhz CPU-NB in 200mhz intervals down to 3200mhz CPU speed. My last test was 3200mhz CPU, 3000mhz CPU-NB. In order to run at that high of CPU-NB I had to bump volts to 1.42 on it.

My next set of tests were by keeping 3800mhz CPU constant and testing different CPU-NB frequencies in 200 intervals back down to 2000mhz.

I've concluded that running this high of CPU-NB, while possible, doesn't make much sense because of the heat generated from it. With my setup, I have to pick which to run with, a higher CPU or a higher CPU-NB. I can't really have both because of the heat generation. If this is the question, based on the memory performance gains in my testing, I can say that it is better to run the CPU faster, otherwise, it becomes the bottleneck to the memory controller.

The memory performance scales much better with the CPU speed as opposed to the CPU-NB speed.

When I was running 3800mhz 1.45v, 3000 1.42v I was about at my heat dissipation abilities. If I nudge too much over 30c I will blue screen.

This is essentially, what we already knew...but for me has provided some removal of the grey areas a bit.

EDIT: Had a 120mm fan blowing on the MOSFET and it was cool to the touch. Didnt' seem to get entirely hot during the night.
 
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Porvlash, Check out my PHenom II Research post, I think you will learn why all this is in there. The post has not been updated in some time but the graphs are there to explain it all.
 
Porvlash, Check out my PHenom II Research post, I think you will learn why all this is in there. The post has not been updated in some time but the graphs are there to explain it all.


Dang man. I thought I had read all your Phenom ii posts but I either didn't read that one or forgot about it.

My best memory performance was not at 3800/3000 like expected. It was actually at 3800/2400. This coincides and validates your theory. The measured performance more or less plateued for 3800mhz between 2200 and 3000 CPU-NB.

The difference between performance at 3800/2200 and 3800/3000 is 0.7%. Yeah you read that right. Optimally though, at 3800/2400, this represents a 23% increase in performance being clock for clock better than at stock (3200/2000).

When balancing heat this is a very good thing because 2400mhz CPU-NB corresponds to very little voltage increase. I was reading a thread the other day in another forum and it was recommended to the person to increase the CPU-NB voltage to match the CPU. /facepalm. People outside of this forum are really in the dark on this one.

Worth noting, this AM3 platform overclocks the same in Vista64 as I have gotten in XP32.
 
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