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Old Aug 7, 2008, 09:45 PM   #106
Psychlone
AMD Overclocking Guru
 
Join Date: Apr 2003
Location: United States Searching for the airspeed velocity of an unladen swallow...
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Now, we're off to a running start:
First of all, here's AMD's overclocking equation: (You're going to want to print all this out - this is easy once you know it... I promise!)

(CPU Multiplier * HTT) = CPU Frequency
(CPU Multiplier / (memory divider) ) = Divisor Ratio (ALWAYS ROUND UP TO THE NEXT INTEGER!!!)
(CPU Frequency / Divisor Ratio) = RAM MHz (* 2 = DDR MHz)
(HTT * HT Driving Strength) = HT MHz

(on the divisor ratio line, there’s a specific note to round up, this means when you have *any* decimal value, even if it’s below .5, please round it UP!)

Memory Dividers shown as decimals for the above equation: (put the decimal in the (memory divider) spot in the second line above)

200MHz (400) = 1/1 (1 / 1 = 1)
183MHz (366) = 9/10 (9 / 10 = .9)
166MHz (333) = 5/6 (5 / 6 = .83333)
133MHz (266) = 2/3 (2 / 3 = .66666)
100MHz (200) = 1/2 (1 / 2 = .5)


HT Driving Strength info (this is just relevant information for your AMD/ATi HT it's called "HyperTransport" & it's a function or 'bus' of the motherboard) - your HTT (that's attached to your CPU multiplier) multiplied by the HT Driving Strength Multiplier below = your motherboard's true HT MHz speed (they're interlocked 'busses')
(i.e. 200MHz HTT multiplied (*) by 5 = 1000MHz HT)
1000MHz = 5X
800MHz = 4X
600MHz = 3X
400MHz = 2X


OK, with all that fresh in your mind, we're going to use the math equation for an easy and quick lesson (less any voltage adjustments - that all comes later...we just want to show how the math works and get familiar with it.

(9 * 300) = (2700)MHz
(remember? - that was your CPU Multiplier times your HTT MHz)
(9 / (.833333)) = 10.8 (round UP, so = 11)
(remember? - that was your CPU Multiplier divided by your Memory Divider shown as a decimal, then rounded to the next higher whole number)
(2700 / 11) = 245.45MHz (* 2 = 490.909MHz DDR)
(remember? - that was your CPU Frequency from line 1 in the equation divided by the sum of line 2 in the equation)
So, you can see your DDR400 RAM sticks are actually running at 491MHZ speed. (this isn't doable with the stock RAM timings)
(300 HTT) * (4X HT) = (1200MHz HT) (this *may* need to be adjusted, but you'll get to all that later - you've got some serious work to do first!)

So, here's the math again without all the verbiage (and so you can get used to the way it looks and works) :

(9) * (300) = (2700)
(9) / (.833333) = (10.8) (rounded = 11)
(2700) / (11) = 245.45 (* 2 = 490.909)
(300) * (4) = (1200)

We're lucky. I have proven the A8R32-MVP Deluxe capable of 1500MHz HT - where most boards out there struggle to attain 1100MHz HT! But again, just because my A8R32-MVP Deluxe *will* run at 1500MHz HT doesn't mean that yours will...don't get that set in your head. And, another thing on HT: as long as you're close to the 1000MHz mark with the actual HT speed (after doing the math of multiplying HTT and the HT multi) - you're just fine...going over 1000MHz doesn't give you a performance INcrease per se, and decreasing it to below 800MHz doesn't give you a performance DEcrease at all...just best to use the math to stay near the 1000MHz mark.
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Last edited by Psychlone : Aug 7, 2008 at 09:53 PM.
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