Overclocking new built AMD system

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January 18, 2009 at 23:36:03
Specs: Windows XP, Athlon 64 X2 4200+
I’m building my first system and I want to overclock my cpu…so I have obvisouly never done it before and I wanted to make sure I do it right the first time. Here is what I’m working with.

CPU: AMD Athlon 64 2X 4200+ 2.2 ghz(it is the 89 Watt version) product page

RAM: DDR2 667mhz (3x1gb) – I think I should be using 800 but it is what it is.

Mother Board: Gigabyte GA-MA770-UD3 product page

CPU fan: COOLER MASTER GeminII S product page

Graphics: EVGA GeForce 9800 GTX+ (512 mb)
Power Supply: 600w Rosewill

I’ve been trying to read up on how to go about this but I’m still a little lost…I understand the basics though. Any guidance would be appreciated.

I don’t start building till Tuesday so I’m just researching till the gear gets here.


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January 19, 2009 at 07:53:33
Overclocked or not, DDR2-667 will bottleneck your system. Why didn't you get DDR2-800?

The theory behind overclocking an AMD system is simple...clock the CPU as high as possible while leaving the rest of the components as close to their default speeds as possible. The easist way is to simply increase the CPU multiplier, but since your CPU is locked from going above 11x, you're gonna have to overclock by increasing the CPU frequency. The problem with that is that any changes to the CPU frequency have a domino effect on all the other frequencies (HT, RAM, PCI-e, PCI, etc), so you have to compensate by changing them as well.

Most of the overclocking will be done using the MB Intelligent Tweaker(M.I.T.) menu:

CPU Clock Ratio = 11x
CPU NorthBridge Freq = auto
CPU Host Clock Control = manual
CPU Frequency (MHz) = 250MHz
PCIE Clock (MHz) = 100MHz
HT Link Frequency = 800MHz
Set Memory Clock = manual
Memory Clock = DDR533

I'm not gonna bother getting into the memory timing settings. You *may* have to increase the CPU voltage to stabilize the overclock though. To do that, set the System Voltage Control to manual, then go to the CPU Voltage Control & bump it up a bit. Try adding 0.025v to the default voltage for starters, then progress in 0.025v increments.

The above settings will run the CPU at 2.75GHz while maintaining the HT bus at 1000MHz (2000MHz DDR), the PCI-e at 100MHz & the RAM should settle in at about DDR2-647 (approx 323MHz). To get the RAM to run as DDR2-667, you'd have to increase the CPU freq to about 257MHz....that will put the CPU at 2.83GHz with the HT bus at 1028MHz.

Get yourself some DDR2-800 RAM ASAP. When you do, all you have to do is change the memory clock to DDR667 & it will run as DDR2-784 (approx 196MHz)...that's with the CPU freq at 250MHz. Bump the freq up to 255MHz & the RAM will run as DDR2-800, the CPU at 2.8GHz & HT bus at 1020MHz.

Here's 4GB (2 x 2GB) of Corsair for just $30:


Here's the same RAM at Frys.com for just $15 but it's currently out of stock. You may wanna keep your eye on it & order when it comes in:


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January 19, 2009 at 09:42:22
Once again, thanks for the fast response!

The reason I’m using DDR2-667 ram is because I already had it. It won’t be a big deal to get new ram.

So to make sure I understand:

First, I will set the CPU frequency to 250MHz and adjust the voltage if the system is unstable. I’m guessing that if the voltage is too low, the system wont post or it will crash and I will have to reset the bios by taking out that little battery? Will I have to change the HT bus to 1000MHz or is that the byproduct of changing the CPU?

If it’s easy to explain, why does the RAM run at DDR2-647 when the memory clock is set to 533? Does it have to do with that 1:1 ratio I’ve heard about?

Next, I will try and bump the CPU freq up to 257 MHz to see if it’s stable there? Can I push it further then that?

I’m trying to understand the benefit of getting DDR2-800. Both seem to get me to the same place, ~2.8 GHz. I’m guessing I will see a performance increase because the memory is communicating with the CPU at a higher frequency but I’m not sure how that relationship works. Will the system be more stable overclocked using the DDR2-800?

Jam, from your posts it looks like I should be using CPU-Z during the overclocking to monitor this stuff…what about for watching the temperature and benchmarking tests?

Thanks again

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January 19, 2009 at 09:48:12
Also, the product page for the CPU lists the voltage as 1.30V/1.35V. Is that the min/max?

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Related Solutions

January 19, 2009 at 15:44:36
"If it’s easy to explain, why does the RAM run at DDR2-647 when the memory clock is set to 533?"

It all has to do with the "domino effect" that I mentioned. Whenever you change the CPU bus, it affects all the other system buses. If you leave the RAM setting on AUTO (or DDR667) & increase the CPU freq from 200MHz to 250MHz, the RAM speed would jump to approx 393MHz (DDR786). Most DDR2-667 can't handle running at that speed so the system would immediately lockup on the reboot.

Why the RAM would run at such an odd number as DDR647 or DDR786 has to do with the CPU multiplier setting. Rather than trying to explain it myself, this article should help...scroll down to "How to Overclock a 754/939 Processor":


"Does it have to do with that 1:1 ratio I’ve heard about?"

No, the 1:1 ratio is for all Intel systems (except the P4) & for older AMD systems prior to the A64. On those systems, the memory controller is on the motherboard & communicates with the CPU via the FSB. Since the debut of the A64, AMD has integrated the memory controller into the CPU & they communicate at full processor speed...in other words, there is no FSB therefore there's nothing to stay in sync with.

"Will I have to change the HT bus to 1000MHz or is that the byproduct of changing the CPU?"

Another part of the domino affect. The HT bus should be kept at 1000MHz or reasonably close. By lowering it to 800MHz, then raising the CPU freq to 250MHz, the HT will automatically increase to 1000MHz again. If it's not lowered to 800MHz, it would run at 1250MHz & just like the RAM, it can't handle running at that speed. It's explained in the article I linked to above.

"what about for watching the temperature and benchmarking tests?"

OCCT can be used for stability tests & also to check temps & voltages:


Doesn't Gigabyte's EasyTune software offer some sort of hardware monitoring as part of the package?

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January 19, 2009 at 17:57:57
Do you know of a chart that shows the relationship between HT bus freq and CPU freq so I can make sure I'm not pushing the HT too hard, or is that not likely to be an issue? (If its in that link, disregard, I will find it)

In the memory dept. (assuming I want my memory to run at the speed it was made for at not overclocked and I my CPU multiplier is locked at X11)

If I keep the ddr2-667, and set the bios to 533, the highest I would be able to set the CPU freq is 270. CPU speed at 2.97GHz.

If I buy ddr2-800, and set the bios to 667, the highest CPU freq is 255. CPU speed at 2.8GHz.
I could set the bios to 533 making the highest possible CPU freq 320...I don't expect that chip can handle that much because I would have to increase the voltage so much and it would be too hot. The chip has a voltage range of 1.3/1.35.

What if I buy ddr2-1066 and set the bios to 800. Then I can get in the 260-270 range (which is what I'm shooting for) and use the memory underclocked in the area of 953MHz? AT least then I know memory will never be a bottle neck problem and I can upgrade processor to a phenom II later on.

I guess what it comes down to is how high I can expect to get my CPU frequency. How high do you think it will go?

As for the other things you mentioned, I don't know what the mother board offers...it doesn't get here till tomorrow. It makes sense that it would. I will check the link you provided regardless.

I read this article and it did a great job of explaining everything:

I'm sure the link you provided says much of the same but I will read it anyway so thanks.

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January 19, 2009 at 18:11:29
Jam, in your original post it looks like you were using 8 as the divider for ddr533. The chart I am looking at lists the divider at 9 for CPU's with a X11 multiplier.

Was there some confusion? Its listed as 8 for CPU's with a multiplier of X10.

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January 19, 2009 at 19:45:43
All I can suggest is that you compare my numbers to the numbers on the chart, then compare them to what actually occurs to see which is correct. I base my method on what is shown in the link I supplied, however that is when using DDR1 RAM, not DDR2. I didn't think the formula changed, but I could be wrong.

Anyhow, here's how I did it:

1st, come up with the memory ratio. In the case of almost all current AMD CPU's, it's based on 800MHz. I suggested setting the RAM to 533MHz so the ratio becomes 533/800 = 0.666

2nd, calculate the Integer Divisor. To do that, divide the CPU Clock Speed by the (CPU frequency x the memory ratio). Using the overclock settings I recommended (11 x 250), here's what I came up with:

2750MHz / (250MHz x 0.666) = 16.5

Since the Integer Divisor has to be a whole number, I rounded up to 17.

3rd, divide the CPU Clock Speed by the Integer Divisor to arrive at the actual memory speed:

2750MHz / 17 = 161.765MHz <--- this is where there's a problem. That number would be correct for DDR1 RAM (doubled it would be DDR323.5) but what I did was multiply by 4 to come up with DDR647.

You can verify that by using a program called A64 MemFreq v1.1. Here's a direct download link:


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