# AMD Overclocking, Detailed!



## de.das.dude (Mar 2, 2012)

So, you got a slick new AMD setup. Now if you are smart, one of the reasons you got an AMD setup is because they are a lot more "fun" to "play" with. And if you are really smart, you will know by "play" i mean overclocking!

But this is your first time you say? Well, no problemo! de.das.dude is here to make your worries away, just make sure you are reading well and doing everything i say.
If, by any change you have queries, be quick to post it here or shoot me a pm!

anyhooz... let the fun begin...






But before that...
There are some basics you need to learn first.


*1. Reference Clock / FSB*
This is a the most important clock in your PC. A lot of other stuff depends on it. Why is it so important? See, all frequencies, like your CPU frequence, your DRAM frequence, etc are derived by multiplying a certain number to this clock.

Unless you bought a pre assembled comp from some company like acer etc, this clock can be varied over a large range indeed.

Smallest increment of the reference clock is 1 unit. Default value is 200

*2. Multiplier*
This is the number that is multiplied with your reference clock to get different frequencies. The name of this multiplier is derived from the clock which it calculate.

_For example,_
CPUMul or CPU multiplier is the one which is multiplied to get the CPU frequency. this is 15 for a 3000MHz CPU
CPU/NBMul is the multiplier which sets the clock for the North Bridge on your CPU die. This is essential for stability default is 10
HTTMul is the multiplier which sets the Hyper Transport Clock. Default is 10


*3. North Bridge*
This is the thing which sets the performance of your memory.
Vary this and the you will see instant gains in memory bandwidth and performance.
This is an often forgotten, but very essential to get that last bit of performance from your CPU.

*Default Value: 2000MHz
Default Multiplier: 10.0x
Increment: 0.5x
Unlock Status: Lower limit 4.0x for all, upper limit unlocked to 20.0x on BE CPUs*

*4. Hyper Transport*
This is how the mobo interacts with the CPU. this really doesnt impact a lot in terms of performance. so dont need to worry about this. Just try to make sure that this is as close to stock as possible.

The versions available are HT3.0 and HT3.1
*default for HT2.0 was 2000Mhz, for HT 3.0 is 2600MHz and for 3.1 its 3200MHz
the max of the HT is always the current NB speed!
*
HTMul depends on the clock. default is 10.0x @ 2000MHz

*5. DRAM:FSB ratio.*
This is going to get complicated now. So brace yourselves for the awesomeness!

This ratio governs the base frequency of your memory with respect to the reference clock or FSB.

If you had been paying attention till now, you will know that the default FSB or RefClk is 200MHz.
So irrespective of DDR2 or DDR3 RAM, your RAM frequency is depended on this particular 200MHz base frequency.
Instead of multiplying the FSB with a multiplier like CPU clock etc, here we multiply it with a "ratio".

You may say, why a friggin ratio?
Well, its because, instead of being more flexible like CPU or NB clocks, the RAM speed has been stepped to some default values.
like, DDR2 400/667/300/1066/1200.. and DDR3 1066/1333/1600/1866/2133...


*How to use this:-
DRAM:FSB = Base Ram freq/ref clock*

For eg, if you are using DDR2 RAM @ 800Mhz
DRAM = 800 i.e base freq is 400 (for ddr2 its= RAM speed div by 2, for DDR3 its = RAM speed divided by 4)
FSB = 200
*just keep in mind base freq is different from actual RAM frequency.*

therefore, DRAM:FSB = 2:1
different ratios give different RAM  frequencies.

*Now, my OC'd ref clock is 275.
You already know the memory divider,

So DRAM=FSB*DRAM:FSB ratio
=2*275= 540.

Since i use DDR2 we multiply with 2 again.
540*2 = 1080. My RAM is effectively running at 1080MHz

For DDR3 instead of multiplying by two in the last step we multiply it with 4.*

*how does this impact overclocking?*
Stay tuned i will cover that in a different thread "RAM Overclocking"!

*6. Voltages*
_*CPU voltage:
default: 1.37V
Max for C2 revision: 1.5V
Max for C3 revision: 1.45V

NB voltatge:
Default: 1.2V
Max for C2: 1.5V
Max for C3: 1.45V

Preffered: 1.3V

HT Voltage
Since you will be leaving the frequency near stock, voltage should be 1.25V*_


WELL, thats about it what you need to know about the basics. Now its time to overclock!


*Overclocking By Raising FSB*

Now, some of you may not have black edition CPUs. But the good news is, that even your CPUs are just as potent in overclocking as BE ones.
BE ones are specifically designed for n00bs who dont know much about overclocking, or dont want to go into too many details while overclocking.
This is good for competitions and stuff, where the clock counts, but, to get the best performance out of your overclock, you must know FSB overclocking.


If you have been attentive you know FSB can be increased by 1 unit.
The first thign to do is to find out the max stable limit of your FSB. Remember, max stable limit is not necessarily the max limit you can set.
Generally the max limit lies within 270-300 for most boards. This means that when your FSB hits >300, you wont be able to stabilize your system NO MATTER WHAT!

*To find the FSB_max:*
1. Go into the advanced settings in your BIOS.
2. Configure CPU Cool n Quiet to [disabled] (this is vital for any overlcock!)
3. Now raise your FSB by 5.
4. Now change the multipliers on CPU, HT, NB, etc so that the CPU, HT and NB stay at stock speeds and dont cause any stability issues themselves. Dont forget to lower the DRAM ratio too. 
Note: no problem if the speeds are lower than stock, but they shouldnt be higher than stock at all.

5. Repeat steps 3 and 4 till you hit a barrier.
_*
Suppose you hit the barrier at 295.
Now you are not sure if the limit is 295 (since you have been incrementing by 5) so you need to go anc check 291,293,294 as well now*_.

this process saves time. A LOT!

now that you have found your FSB limit, its time to overclock the CPU through it. Same procedure like finding the limit, only this time you will let the CPU Multiplier stay at default, and rest others will be changed to ensure stock speeds.

1. This time take increments of 10 till 230
2. Then after that take 5 increments till 260.
3. Again, like before if you hit a crash, start from the last incremented value and increase by 1.
4. After getting a particular FSB value say 237, where it is now stable at stock voltage, we need to push it further!
5. Bump the FSB by 5 and set CPU or core voltage at 1.4V (go straight to 1.4V, i say this from experience  )
6. Then keep on incrementing by 1 and rebooting. [ Note: we are only lookin for a OC that boots and sits in the windows home screen, nothing more stable is need at this point ]
7. If you hit a bump, increase your CPU Voltageby one step(press "+" key once)

You will soon get to a fixed value for your OC.

Here is an ensemble of all the clocks possible for Stock AMD cooper heatpipe coolers:-
_<list will be added soon>_

Now head over to the Download section of this thread below and download all the stuff i listed there.

*Checking Your System Stability*
1. Memory Stability.
After POST, boot from the CD and memtest will run. run it for atleast 10 mins. IF you do have instability of OC, they show up in 10 mins.\
If you get errors, goto BIOSs and make sure the effective memory frequency is equal or less than stock value. More details in the Memory overclocking section.

2. CPU Clock stability
Now that your memory is stable. Boot into windows, setup prime95 and run GIMP from the tests menu.
For complete stability you need to run it atleast overnight for 8hrs. Make sure you have speedfan installed and running as well so that you can monitor temperatures.

If your system is instable, bump up the voltage by the smallest increment and try again. Do this till you reach the max voltage i specified before (basics section). If you hit the max voltage and yet cant stabilize, lower the ref clock by 1 or increase the NB.

*Overlclocking the North Bridge*
Sometimes an equally overclocked NB is required to stabilize a CPU overclock.
To overclock your NB, just use the NB multiplier for this job. And up the voltage in steps if you get instabilities.
*To check for NB stability boot into Memtest and run it.*

Here is a list of tables of NB and their corresponding voltages (table for Deneb and Thuban).





*Note:* Sometimes when using dual channel memory config you might end up using a bit more voltage. For Example, i need 1.4V to get 2700stable in dual channel DDR2 1080

*Overlcocking HT*
Simply no need of this. Put your HT at 2000MHz or the board default.. This barely affects performance.


*Overclocking A Black Edition CPU*
Advantages of a BE CPU are:-
1. Upward unlocked multiplier for the CPU and NB
2. No need to worry about memory dividers

Overclocking is pretty simple now.
*First the CPU:-*
1. Increase multiplier in the smallest increment possible,
2. boot to windows
3. Check for stability with prime 95
4. Increase voltage by smallest increment if unstable
5. Test with prime again.
6. Repeat all steps if stable.

*ditto for NB.* Only this time check stability with Memtest.



*DOWNLOADS SECTION*
1. Prime95

Run the GIMPS test. Have internet connected when doing the first time.
2. AMD Overdrive
3. Speedfan
4. memtest (burn it to a bootable CD)

*Protips:-*
1. Never be scared of BSODs they dont do any damage.
2. Always be hydrated
3. Patience is the key!
4. Dont skimp on the tests!
5. respect mah authority!


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