Returning downclocked RAM to native speed

TheAscension · Aug 25, 2008, 01:54 AM

I have a new system where my 1066 RAM is downclocked to 800 because of the Athlon 64 X2 5000+ I'm using. However, I would like to clock it back up to 1066 but I'm not sure how to go about doing that. I'm not really looking to overclock the CPU so much, but rather return the RAM to it's native 1066 operating frequency.

***temeteus82*** · Aug 25, 2008, 02:12 AM

The problem is that AMD has integrated the memory controller to the CPU so I think that there is no way to goto 1066MHz RAM speed without overcloking the CPU itself. I'm not 100% sure about this but it does make sense to me.

cozumel · Aug 25, 2008, 05:55 AM

It might be useful to look at some AMD overclocking guides so that you know how the AMD CPU and RAM speed are linked. By using one of these guides you should be able to get you DDR2 up to full speed.

Here's one that gives some good background on the prinicpals used and the link between HTT and memory speed. There are a plethora of other guides available too (google for them) and the information is out there.

Overclocking Guide - Athlon64 and General FAQ

By all means return here if you are confused after all your research and require further guidance. There are plenty of AMD gurus here at DH, but I am not one of them.

TheAscension · Aug 25, 2008, 11:59 AM

Well I spent much of yesterday reading about this. Trouble is that all the overclocking I've done in the past (quite a bit actually) has been on AMD K7 processors. The AM2 K8 architecture is very confusing and much different, primarily because of the on-die memory controller (no FSB) and HTT.

I will read some more today and further solidify the questions I have then I'll post some more questions to this thread. Thanks for the replies!

TheAscension · Aug 25, 2008, 11:48 PM

From the stickied post at the top (great write up BTW):

Quote:

Originally Posted by psychlone

AMD Overclocking Equation:
(CPU Multi) * (FSB) = (CPU Freq)
(CPU Multi) / (Memory Divider) = (Divisor Ratio)
(CPU Freq) / (Divisor Ratio) = (RAM MHz) (* 2 = DDR MHz)
(NB Multi) * (FSB) = (NB Freq)
(HT Multi) * (FSB) = (HT Freq) **
**note: the HT Multi is usually shown as a MHz option rather than a multiplier of the FSB, but in fact, it is a default of 10X the FSB
Also of note is that your HT *MUST* be < or = the resulting NB Frequency or you will not be stable.

Memory Dividers for use in the equation above
I have included every conceivable way that these dividers can be displayed for every AM2/AM2+ BIOS. Use the DECIMAL value in the equation above and use one of the corresponding values for your specific BIOS. I've only included the 800MHz and the 1066MHz values, as this is what the majority of us are using.

533 = 1066 = 16:6 = 8:3 = (8 / 3 = 2.6666666) = 2.6666666
400 = 800 = 12:6 = 6:3 = (6 / 3 = 2) = 2

I've read through the entire guide and the trouble is that I don't have the BIOS options that I think I need to clock my RAM back up.

Here are my BIOS options:

1. HT Link Frequency (200 MHz - 1GHz)
2. CPU Clock Ratio (anything upto 13)
3. CPU Host clock control (200 MHz - 500Mhz)
4. Set Memory Clock (choice of DDR 400/533/667/800 with AM2) or (X2.00/2.66/3.33/4.00/5.33 with AM2+)

The only thing that relates to those equations above that I have any control over is the CPU Ratio. Ultimately I would need to have control over the "divisor ratio" and the "CPU freq" in order the change the RAM speed, Correct? I do have control over the CPU frequency but I don't (as far as I can tell) have control over the divisor ratio (or memory divider)

cozumel · Aug 26, 2008, 11:21 AM

I can't give you anything precise on how the htt works as I've never had an AMD CPU.

All I can say is that you do appear to have the settings there to control the memory speed via the CPU Host clock control and the memory ratios (Memory clock) within the BIOS:

Quote:

CPU Host clock control (200 MHz - 500Mhz)
Set Memory Clock (choice of DDR 400/533/667/800 with AM2) or (X2.00/2.66/3.33/4.00/5.33 with AM2+)

So, order to get to an exact DDR2 1066MHZ you would need either:

Host clock @ 266 / Memory clock x2
Host clock @ 200 / Memory clock x2.66

and

Quote:

(HT Multi) * (FSB) = (HT Freq)

And, I think, but I'm not sure, to get an HTT at or around 1000MHz you would need to do one of the of the following:

HTT Multi (CPU clock control) @ 5 * FSB (CPU Host clock) @ 200 = 1000MHz
HTT Multi (CPU clock control) @ 4 * FSB (CPU Host clock) @ 266 = 1066MHz (A little overclocked and may cause probs if nb speed is lower than this)

I only think that your 5200+ has a stock HTT of 1000MHz but I could be wrong.

I've probably got this all wrong though as I really know nothing 'bout AMD platforms. I haven't read any of the guides as there was no point seaa I don't use AMD CPU's but I definitely reckon you should keep on reading. Hopefully someone else will come here to clarify your requirements

cozumel · Aug 26, 2008, 11:42 AM

Your CPU will not support 1066MHz DDR2

What I typed above won't work

Quote:

Hi there,

DDR2-1066 RAM will work with the 5200+ CPU, but it will run at DDR2-800.

The Integrated memory Controller on X2 CPU's supports a maximum of DDR2-800

For DDR2-1066 Support a Phenom CPU will be needed with the new IMC.

On the plus side if you intend to Overclock the 5200+, then having DDR2-1066 RAM that is capable of running in excess of 800Mhz might give you addittional headroom for OC'ng.

Found this answer in the AMD forums. See the the full thread here.

Edit: Having read that AMD thread some more, it may be possible to overclock the 5200+ and get your RAM running @ 1066 (or faster) anyhow. It all depends on how the individual board, CPU & RAM modules like playing together. The 5200+ just limits the DDR2 speed when the CPU is running at stock. So, I guess the ball is in yourt as to what to do now...

TheAscension · Aug 26, 2008, 12:36 PM

Great find Cozumel. I really appreciate your help. I was beginning to think that I may be SOL. There were some good suggestions in your previous post but those suggestions involved features I don't have access to (i.e. memory clock x2.00/2.66/...) because they're only for AM2+ processors (I only have an AM2). Very good thinking though.

However, I may just return the X2 processor for an X3 since I'm within 30 days from Newegg purchase. The X3 will give 1066 speed and it's only $43 more than the X2.