Dolk's Guide to the Phenom II

[Raxen18]

I don't know if this will help, but on my board there are separate voltages for HT and NB, as well as a whole slew of different settings.



The numbers above were all punched in. With the exception of CPU, CPU-NB, and DRAM voltages, the numbers were the lowest in the range that could have been applied.

I think the 1.8v you're seeing is labeled as NB 1.8 Voltage on my board. There should be another voltage labeled as NB Voltage.

 

[Dolk]

Yeah the NB 1.8v is the NB PCIE PLL you were right Quiet. The three settings you should mess with is the CPU Voltage, CPU/NB Voltage, and DDR DIMM Voltage. Everything else keep at Auto or Stock, which every your MOBO supports.

 

[QuietIce]

So that's what the VDDIO is? Glad you found out (though I'd like to know where you found it). All I could do was quote the white paper ...

 

[chewonthis]

I don't know if this will help, but on my board there are separate voltages for HT and NB, as well as a whole slew of different settings.



The numbers above were all punched in. With the exception of CPU, CPU-NB, and DRAM voltages, the numbers were the lowest in the range that could have been applied.

I think the 1.8v you're seeing is labeled as NB 1.8 Voltage on my board. There should be another voltage labeled as NB Voltage.

HT is in the southbridge so if you want to raise HT you need to add HT or SB volts depending on the motherboard...........No real benefits.....2200-2300 around 4gig. If your benching 3d and xfire it helps to jack it to 2500 at 5gig and 2700 at 6gig.......jacking it to 2700 with a low clock will hurt scores though......

 

[gmony01]

Nah those two should be on two different settings. If you take pics or link your BIOS manual I can see what I can do on this end with that information.

I'm headed out town for the weekend Dolk, so I'll send some after. What does the NB PCI PLL do any way? I also tried to adjust the 1.110 value for NB Voltage to 1.2054 in AOD and it automatically reset back to 1.110. Maybe this board doesn't support adjusting the voltage for NB?

 

[Dolk]

Chew, the HT is located in the CPU, not the SB. The NB houses the HT voltage as well as the PCI-E voltage. I've never played around with that setting just left it as is.

Quite, I compared the voltages to my board's BIOS settings. I knew that the stock voltages wouldn't be far from mine.

 

[QuietIce]

Chew, the HT is located in the CPU, not the SB. The NB houses the HT voltage as well as the PCI-E voltage. I've never played around with that setting just left it as is.

Quite, I compared the voltages to my board's BIOS settings. I knew that the stock voltages wouldn't be far from mine.

So, basically, anyone cranking up the PCIe clock may want to increase the "NB 1.8v"? Hmmm, that may be what was holding back my 9950 on a 790GX chipset. Increasing the on-board video clock (not PCIe) seems to help the OC - and don't ask me why, I still can't figure that one out! But the OC may go better IF I have an adjustment for that on the 790GX board, which may not be the case.


One other thing - are we sure the HT node is on the CPU? I thought the same thing as you when I read chewonthis's post but after a little research into HyperTransport I'm not 100% sure anymore. The HT node being on the SB or even the NB chipset could explain why some of the older boards (i.e., 590 chipset) can't run the AM2+ CPUs regardless of BIOS update ...

 

[chewonthis]

Chew, the HT is located in the CPU, not the SB. The NB houses the HT voltage as well as the PCI-E voltage. I've never played around with that setting just left it as is.

Quite, I compared the voltages to my board's BIOS settings. I knew that the stock voltages wouldn't be far from mine.

I beg to differ bud, you will be hard pressed to run this HT clock without increasing the SB volts on the gigabyte

I can duplicate this on air so it has nothing to do with the cpu being cold or having insane volts going to it.

BTW increasing HT to 2700 hinders performance if the system is not maxxed out......only beneficial in crossfire and with the cpu clocked high....... this is where I have noted scaling.......4gigcpu/ 2300 HT, 5gig cpu/2500HT, 6gig cpu/2700HT havent studied it further than this but I'm quite sure CPU NB must be scaled as well to note the performance gains.

Note the scaling only thing changed was HT = 92 points gain in 06

 

[QuietIce]

I beg to differ bud, you will be hard pressed to run this HT clock without increasing the SB volts on the gigabyte

I can duplicate this on air so it has nothing to do with the cpu being cold or having insane volts going to it.

BTW increasing HT to 2700 hinders performance if the system is not maxxed out......only beneficial in crossfire and with the cpu clocked high....... this is where I have noted scaling.......4gigcpu/ 2300 HT, 5gig cpu/2500HT, 6gig cpu/2700HT havent studied it further than this but I'm quite sure CPU NB must be scaled as well to note the performance gains.

Note the scaling only thing changed was HT = 92 points gain in 06

Darn! I was hoping you had links showing more about the physical implementation of HyperTransport. I've read through a lot of stuff on HyperTransport.org but so far none if it mentions the physical location of the HT hub. Even though I'm an amateur I like reading through various white papers to see how those nit-picking little details work.


I am sure there are HT nodes in the SB chipset (whether the HT hub is there or not) and the increased voltage may be required because the nodes would be stressed more with a higher HT Link speed ...

 

[Dolk]

I have always read that it is controlled inside the CPU-NB area. Which makes sense because your HT can never go higher then your CPU-NB Frequency, which in most cases it should never be that high.

I am very interested in your work there Chew. Any chance you can explain more on what you have found out? And I also can't wait to get my hands on the 955, my 940 is getting boring till my LN2 arrives

 

[chewonthis]

I have always read that it is controlled inside the CPU-NB area. Which makes sense because your HT can never go higher then your CPU-NB Frequency, which in most cases it should never be that high.

I am very interested in your work there Chew. Any chance you can explain more on what you have found out? And I also can't wait to get my hands on the 955, my 940 is getting boring till my LN2 arrives

Sure,

I've found with ddr II there is a sweet spot with cpu and NB speeds.....

Seems that they work in harmony the most with NB 400mhz below CPU speed.....of course this doesn't help much when on ln2 as I've yet to break 4750 NB speeds.....

Seems to be a wall around 1800 with ram with AM3 chips, it also seems that increasing NB volts ( not NBvid ) topples this wall to a certain extent, side effect is you lose HT clocking ( at least with this particular board ).

I have a few of the same boards so I will retest to see if its this boards limit or a limit period.

Still exploring the full potential of these chips, learning new stuff everyday....I plan to explore HT a little further, maybe cool the SB see if there any gains.....2900 is not doable yet on 2 boards we have used so far.

 

[Dolk]

very interesting findings. Similar to what I have seen with my 940. Although I never did manage to fully explore the HT region for that long. I liked the CPU-NB more so. I've found that you can not manage 3000mhz unless your CPU is a bit chilled, at least with mine. But I do find that you must increase it to keep upping your CPU frequency.

 

[chewonthis]

very interesting findings. Similar to what I have seen with my 940. Although I never did manage to fully explore the HT region for that long. I liked the CPU-NB more so. I've found that you can not manage 3000mhz unless your CPU is a bit chilled, at least with mine. But I do find that you must increase it to keep upping your CPU frequency.

Preety sure i've had 3200 NB on air, Oh and another thing to note 1/1 cpu and NB ratio equals out to a huge performance hit ( no clue )

I dunno about the rasing NB to clock cpu more.......I've downclocked it and validated extremely high ( 6gig ) no issues......in fact underclocking it and NB Vid reduces heat which may net you a higher validation on air.....On the other hand I have seen it hinder max clocks if its to high.........happened to me tonight on LN2......

 

[Dolk]

You could only do 1:1 on the lower clocks though. I'm pretty sure that i can't accomplish it with my 940 at 3.7ghz. I have a tough enough time getting to 3.0ghz on Water. No idea why but it hates being that high unless the CPU is under 30C load.

 

[chewonthis]

You could only do 1:1 on the lower clocks though. I'm pretty sure that i can't accomplish it with my 940 at 3.7ghz. I have a tough enough time getting to 3.0ghz on Water. No idea why but it hates being that high unless the CPU is under 30C load.

Might be becasue you arent pushing ram hard........


I've noted in order to push ram hard you need to push NB hard and vice/versa.

 

[oldbrave]

I'd like to throw this out there!
Has anyone gotten any changes in their OC by altering the CPU VDDA Voltage setting? I haven't been able to find out what it is or what it does!

 

[QuietIce]

VDDA is the voltage for the CPU core multiplier PLLs - nominal 2.5v ...

 

[gmony01]

Hey guys, hope you all had a wonderful weekend. Anyway, I posted a link below for the manual to my mother, it in pdf format. If you scroll down to page 29 it shows the voltage settings available for my motherboard. What is the CPU PLL Voltage Setting for?

http://download213.mediafire.com/d29k00i1sszg/hzgyngnhxmm/A79A-S-En-Manual-V1.0.pdf

 

[Psykoikonov]

Hey guys, hope you all had a wonderful weekend. Anyway, I posted a link below for the manual to my mother, it in pdf format. If you scroll down to page 29 it shows the voltage settings available for my motherboard. What is the CPU PLL Voltage Setting for?

http://download213.mediafire.com/d29k00i1sszg/hzgyngnhxmm/A79A-S-En-Manual-V1.0.pdf

PLL = Phase-locked loop, article here, wiki here.
Some Intel overclockers have found that increasing this gave slightly higher overclocks from what I found when I searched.

 

[QuietIce]

What is the CPU PLL Voltage Setting for?

See post #237.

The "CPU PLL" is the circuit on the northbridge that controls the four core multipliers - one PLL sub-circuit for each core. Nominal voltage is 2.5v and, so far, I've never heard of any one changing it. Experimentation welcome ...