Help with Oc'ing an FX-8350

[nicehat]

Beginner OCer and I read up alot of tutorials and FAQ's. Unfortunately there isnt alot of info out there on my motherboard specifically the MSI 990FXA GD80 v2. The image attached is of the control center app that Ill be using. There are a few terms there that are unfamiliar to me, like

 

CPU NB V

SB V

CPU PLL V

NB V

 

NB, SB = North and southbridge? Do I need to mess with those? 

Whats the difference between CPU NB and NB

Whats CPU PLL

 

Ive been reading that my board doesnt have Load line Calibration and that it sufferes from droop. Theres one guy out there that gives the compensentory voltage needed, but Im not sure.. Any help with this topic? Getting into OCing is making my head spin. 

[helping]

Northbridge is the chip that serves as the terminal between your GPU/RAM and the CPU. Southbridge usually functions to serve most other things connected to the board i.e.HDD controllers, audio, USB etc. Out of the two the Southbridge would have less throughput. You can think of them in terms of direction, they're named appropriately because the SB is the chip that would be to the right of your PCI slots and NB is the chip above your PCI slots.
 
For NB you might have to mess with it (lower hz or raised voltage) when overclocking. You don't have to worry about SB at all. CPU PLL is somewhat of a hazy topic, I doubt you'll get a clear answer ever here, but generally it's best to not touch it and just mess with CPU voltage. Is it possible to disable? Or at the very least leave it at stock and not 'Auto.'
 

disable C1E, PowerNow/Cool N Quiet, C6, CPU spread spectrum) and adjust the multiplier up one setting at a time until instability in a stress test.

During the stress test, I like to watch voltage in CPU-Z. See how low it goes under load to know your voltage drop/vdroop. Once you know that, you can manually apply CPU vcore offset to compensate for the drop, since you and I both don't have LLC per se.

do this. You can use software to get an idea of what your stuff can do, but ultimately set your settings in BIOS once you find what is your approximation of stability. You won't need to bother with CPU PLL/PLL overvolt unless you're doing some pretty high OCing, which you don't seem to be doing.

[TymmVonD]

I've been told to always use the Bios OC, not software.

 

For a noob OC, keep everything auto, set your RAM manually, (disable C1E, PowerNow/Cool N Quiet, C6, CPU spread spectrum) and adjust the multiplier up one setting at a time until instability in a stress test.

 

During the stress test, I like to watch voltage in CPU-Z. See how low it goes under load to know your voltage drop/vdroop. Once you know that, you can manually apply CPU vcore offset to compensate for the drop, since you and I both don't have LLC per se.

[nicehat]

Thanks guys, what multiplier do you suggest I start with? (would 200 X 22 be fine?) How long should I run Prime 95 for after each bump? Just to confirm:

 

1.) Increase mult until instability

 

2.) increase CPU voltage minimally until Prime reports CPU stable

 

3.) Rinse and repeat? 

 

Also, I had to manually punch in Ram speeds and timings into the BIOS... Will this count as an overclock in some way? Will it affect my CPU OC headroom?  

[Mentalguy]

Thanks guys, what multiplier do you suggest I start with? (would 200 X 22 be fine?) How long should I run Prime 95 for after each bump? Just to confirm:

 

1.) Increase mult until instability

 

2.) increase CPU voltage minimally until Prime reports CPU stable

 

3.) Rinse and repeat? 

 

Thats the basics of it, just go to a temp you are comfortable with(about 60c on AMD).

[TymmVonD]

Thanks guys, what multiplier do you suggest I start with? (would 200 X 22 be fine?) How long should I run Prime 95 for after each bump? Just to confirm:

 

1.) Increase mult until instability

 

2.) increase CPU voltage minimally until Prime reports CPU stable

 

3.) Rinse and repeat? 

 

Also, I had to manually punch in Ram speeds and timings into the BIOS... Will this count as an overclock in some way? Will it affect my CPU OC headroom?  

The headroom comes from how high your RAM is rated for. You set the RAM lower than rated and OC using FSB/Bus freq, which OC's your RAM. Don't worry about that now. You'll get there eventually. x22 should be fine at stock voltage. 

 

In my case, I have to bump voltage up from 1.375-1.38 to have stability at 4.4GHz and add an offset of vcore +0.05v, but my chip may be a weakling. I've seen higher with much less V. Plus my mobo is junk(4+2 phase). Every adjustment has to be done old school with a calculator.. Nothing compensates for micro adjustments.

[nicehat]

Ok just to update, I got to 4.4 GHz but at high volatage (1.4135). I had to increase the volts because Prime 95 kept failing cores 5-8. As I increased voltage failed cores dropped and now it seems stable. Do I have a bad chip or something? Are these voltages fine? 

 

-EDIT- As soon as I figure out a stable config I plan on setting these values in the BIOS

[MG2R]

 CPU PLL is somewhat of a hazy topic, I doubt you'll get a clear answer ever here, but generally it's best to not touch it and just mess with CPU voltage.

 

If anyone's interested:

 

PLL stands for Phase Locked Loop and is part of the clock distribution system in a CPU. The clock in a CPU runs a given frequency (4.2GHz for example). This frequency is derived from the base clock by multiplying that base clock with a given number (the multiplier you set in the BIOS). The PLL makes sure that this higher frequency is phase locked to the base clock, meaning that the two clocks are in sync with eachother (see figure below). If this is not the case, all the digital signals going to and from the CPU would be misinterpreted by the rest of the system (a bit that GPU receives now, could be the bit should've received a clock cycle sooner).

 

PLL.PNG

This figure shows the base clock (top) and the CPU clock (bottom). In this example, the multiplier would be two.

 

Usually this piece of hardware has a set voltage it works at (Vpll). For extreme overclocking, it can sometimes be beneficial to overvolt, for the same reason a CPU gets more stable when you give it more voltage. On the other hand, overvolting it might make it unstable as well and actually make you overclock less. If you don't know what it is, you should probably just leave it as it is.

[TymmVonD]

Ok just to update, I got to 4.4 GHz but at high volatage (1.4135). I had to increase the volts because Prime 95 kept failing cores 5-8. As I increased voltage failed cores dropped and now it seems stable. Do I have a bad chip or something? Are these voltages fine? 

 

-EDIT- As soon as I figure out a stable config I plan on setting these values in the BIOS

Thats not very high. With my offset of +.05 it idles at 1.42v