Please note that this is aimed at older K8 Athlon X2's not the newer K10 Phenoms which has different settings and methodology for overclocking
- if you are new to overclocking you might still benefit from some of the following however the forumalae provided are specifically for K8 not K10. - Best Wishes Kazgirl
Seeing a lot of Q's lately about overclocking etc and thinking of this reply I did to another post, and thought it may be of some help to others, I'm in no way an expert, and this is what I've come up with myself through my own overclocking experiences.
OK I pretty much did all this in reply to someone asking how they could increase thier RAM Frequency, as they had found how to change the CPU Frequency and so I wanted tot ry and explain that the RAM frequency was linked to CPU Speed and RAM divisor etc......and so it began there....
And well I thought it may be of benefit to others.....
I know it's quite complicated, to follow with all the equations, but it takes some of the guesswork out of overclocking, or at least so I found.
I used these formulae to set up a spreadsheet, so now all I have to do is enter the values I want to change , i.e. CPU Freq, CPU Mulitplier RAM Divisor etc, and then the spreasheet applies the formulas and gives the correct values, and it works like a gem for me....unfortunaetly I cannot post the spreadsheet itself, but if someone would like a copy then feel free to PM me.
Its a basic rundown (as I understand it of PC operation) and the link between each of the main components.
Anyway here it is...hope it's of some help, if anyone would like to add anything or thinks something needs changing then let me know and I will edit it accordingly.
Essentially for your PC to run smoothly everything has to work together, so all the components are linked together, for example, theres no point having an ultra fast CPU if the rest of your system is unable to keep up with it, i.e. your RAM, HT speed etc. etc
Ideally for best performance your RAM should run at the same speed as your chipset bus speed i.e on a ratio of 1:1, your chipset bus is essentially what carries all the data between all your various components, so from/to your CPU - RAM - VGA etc.
This is why when you OC your CPU you can only OC it to a certain level depending on the rest of your components.
The formulae used go something like this:
A) CPU SPEED = CPU FREQ X CPU MULTI
B) HTT SPEED = CPU FREQ X HT MULTI
C) RAM DDR2 SPEED = RAM DDR SPEED x 2
D) RAM DDR SPEED = (CPU SPEED / RAM DIVISOR ) x2
E) RAM DIVISOR = CPU MULTI / RAM DIVIDER RATIO
F) RAM DIVIDER RATIO = RAM ACTUAL SPEED : CHIPSET HT BUS SPEED
G) RAM ACTUAL SPEED = (DDR2 SPEED / 2) / 2
H) CHIPSET HT BUS SPEED = NOMINAL MOBO CHIPSET HT SPEED / NOMINAL HT MULTI
So using the above and starting from the bottom of the list and working up using the stock settings for the following:
CPU - AMD x2 6000+ CPU Freq: 200Mhz - CPU Multiplier: x15 CPU Speed: 3000Mhz
Motherboard - M2N32SLI - Chipset HT Bus Speed: 1000Mhz - HT Multiplier: x5
RAM - DDR2-800 - DDR2 speed: 800Mhz
H) CHIPSET HT BUS SPEED = 1000Mhz / 5 = 200MHz
G) RAM ACTUAL SPEED = (800Mhz / 2) / 2 = 200Mhz
F) RAM DIVIDER RATIO = 200 : 200 = 1:1 i.e 1
E) RAM DIVISOR = 15/1 = 15
D) RAM DDR SPEED = (3000Mhz / 15) x 2 = 400Mhz
C) RAM DDR2 Speed = 400Mhz x 2 = 800Mhz
B) HTT SPEED = 200 x 5 = 1000Mhz
A) CPU SPEED = 200 x 15 = 3000Mhz
So looking at this we can see that if we change the CPU FREQ form 200 to 210 and then work through the list making the appropriate changes we can see what effects it has:
A) CPU SPEED = 210 x 15 = 3150Mhz
B) HTT SPEED = 210 x 5 = 1050Mhz
C) RAM DDR2 SPEED = 420Mhz x 2 = 840 Mhz
D) RAM DDR SPEED = (3150 / 15) x 2 = 420 Mhz
E) RAM DIVISOR = 15/1 = 15
F) RAM DIVIDER RATIO = 210:210 = 1
G) RAM ACTUAL SPEED = (840 / 2) / 2 = 210
H) CHIPSET HT SPEED = 1050Mhz / 5 = 210
So from this we can see that by just changing our CPU FREQUENCY it also changes the others as well,... as our RAM speed has now increased from 800 Mhz to 840 Mhz, and our HT Speed has increased from 1000Mhz to 1050Mhz even though all we have manually changed is the CPU Frequency.
Its by manipulating these settings that we overclock our computer and so understanding how each change affects the others is an important part of being able to overclock.
The above only takes into consideration the speed links involved, the next part is to consider the power changes needed in order for the components to be able to run at the higher speeds, as an increase of speed will eventually mean the need for more power, but with more power comes more heat, until you reach a point where the amount of heat being generated prevents being able to push more power and in turn more speed to the various components.....so then you need to look to reduce the heat, so that power can be increased and so can the speed etc...and so the whole balancing act starts all over but now with power and heat.
Until at one point you are limited by either
(a) Your Cooling ability
(b) Power limits
(c) Indivdual components capability for (a) or (b)
So there you have it....lol....the basic concepts (at least as I understand it) of Computer engineering and overclocking.
Hope its of help, I know it'll take some time to take it all in, it took me a while too....lol...piecing everything together through trial and error, and a lot of time....
Hope its of some help to you.
to overclock the memory all you do is increase the cpu freq?
Yes, its not possible to overclock the RAM by changing the RAM Frequency independently of the CPU Frequency.
You can change the RAM frequency by applying a different RAM Divisor. - But this would normally be underclocking your RAM, i.e. if you wanted to increase your CPU frequency to increase your CPU speed further, but that this value would cause your RAM at its optimal divisor to try to run at a speed that exceeded its capability, you can lower the RAM Divisor.
For example using my post above, the optimal divisor is a ratio of 1:1 with the chipset HT frequency, which we know to be 200Mhz, as the mobo is specified to run at a nominal chipset speed of 1000Mhz with an optimal Mulitplier of x5, so dividing the nominal chipset speed by the x5 multiplier gives us the nominal HT Frequency of 200Mhz.
BTW it is optimal as it means that for every 1Mhz of speed that the RAM has for passing information the HT has an equal 1Mhz of speed to carry information, if it were to change so that the RAM was dealing with information faster than the HT could carry it away, then that would cause the RAM to start making errors..
Think of Our RAM like a chain of people passing boxes from one end where it receives the boxes from (Windows), to the other end where they get taken away by (HT), as long as the boxes at the removal end of the chain are being taken away by (HT) at the same speed that the Chain (RAM) is passing them, then everything runs smooth, if however the boxes start being passed by (RAM) faster than they are being taken away by (HT), then you end up with a pile of boxes building up at the end of the chain, until eventually there's no more room for any more boxes, so the whole chain (RAM) has to stop working.
Overly simplified I admit, but you get the idea...I hope....lol.
The DDR2-800 RAM that I have is rated at an actual speed 200Mhz, i.e. 800Mhz @ effective DDR2, divided by 2 = 400Mhz @ effective DDR, divided by 2 = 200Mhz Actual speed.
So 200Mhz Chipset speed and 200Mhz RAM Actual speed we can see is a ratio of 1:1.
So the boxes would be passed from RAM and taken away by HT at a rate of 1 box passed 1 box taken away so everything works fine.
But we can choose to run our RAM at a less than the optimal ratio, so even though our RAM is rated for DDR2-800 or 800Mhz DDR2, we can manually set it to run at a lower rating of say DDR2-667, so now if our Chipset Speed is 200Mhz and our RAM actual speed (now artificially reduced) is 166Mhz (i.e 667Mhz /2 = 333Mhz / 2 = 166Mhz) we can see that 200:166 is no longer a ratio of 1:1
Well there are really 2 basic approaches to overclocking memory:
1. You can go for more speed, i.e. increasing the RAM Frequency, which is done by increasing the CPU frequency, which results in overclocking your CPU as well, so its more of a system overclock, than just a memory overclock. This is the easiest and most common technique, due to its relative simplicity over the second method.
2. You can improve the memory timings, this will overclock your RAM only, and you do this by tightening the RAM timings from say CL5 to CL4, i.e. 5-5-5-15 2T to 4-4-4-12 2T. With the lower figures being the better.
The above are the basic memory settings as Memory timings can be changed to different values, with experimentation, and in all honesty I have not yet looked into the details of memory timing as a way of overclocking RAM, that is a subject that I intend to try and learn more about, but at present I can't really say I have a full understanding of it.
My basic understanding of it at the moment is:
Each of the figures 5-5-5-15 2T, serves a purpose in the RAM's operation, generally with each number representing the amount of time it takes to perform it's particular function, kind of like an assembly line if you like where a-b-c-d-e and fT each has their own job to do, before the end product can be sent out, in this case the end product being the data to be sent to the CPU.
So the quicker that each of them does they're own seperate function the quicker the end product is ready to be sent out.
As I say I havn't yet looked into the subject of RAM timings in any depth, so can't offer much specific information about this at present.
also to what did you set up the volt of the cpu?
Well I initially had it set to the stock voltage i.e. 1.4v, but was having stability problems so I ended up rasing my voltage to 1.525v, as I have water cooling the extra heat from this wouldn't be a problem, and even at this voltage my temps are well within a safe range, i.e idle temps are 37C and I've yet to see my load temp go over 48C.
and the volt of the memory??
My RAM is rated by the manufacturer for up to 2.3v at its highest EPP Profile, so I put my RAM Voltage to this figure, I havn't bothered trying it at a lower voltage, as I'm happy to let it run at the 2.3v max that the manufacturer has rated it at.
Hope this is of some help to you.
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05:01 AM by