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Opteron 148 w/ SLi DR


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Hey. I just got my new rig and stuff. Everything is in my sig. Im ready to do some overclocking with my Opteron 148. Ive read the overclocking stickies but, its all a big mess and I am not VERY clear of overclocking. Any tips would be nice.

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What bits are not clear to you?


Do you understand what these are?



- DRAM:FSB ratio

- HTT frequency

- LDT ratio

- CPU Ratio

- Memory voltage

- CPU voltage (Vcore)


A CPU operates at a given frequency, eg 1800Mhz.

This frequency = CPU FSB x CPU ratio.


Default FSB on the Athlon 939 CPUs = 200Mhz.

So a 1800Mhz CPU has a default CPU ratio of what?

200Mhz x What = 1800Mhz.

You should be thinking x 9.


Your CPU runs at 2200Ghz

Therefore the default CPU ratio = x11.


The key to overclocking the CPU is to change the FSB.


So if you increase the FSB from 200Mhz to say 250Mhz what would your CPU operate at?


250Mhz x 11 = 2750Mhz.


Now that looks easy but you need to consider a few things,

overclocking the CPU means it is going to use more power.

Which means you may need to increase the Vcore voltage.


And by default, the memory frequency operates at the say value as the CPU FSB.


So if you increase the FSB to 250Mhz, the memory will also run at 250Mhz (500DDR).


Because of this you may need to adjust a few of the memory timings,

especially the Max aysnc latency and read preamble delay options.


However you can make the memory run at a lower frequency by using the Dram:FSB ratio option.


1:1 means (FSB x 1) / 1 = Memory frequency. :).



Also the 939 CPUs have something called the Hypertransport BUS.

This by default is 1000Mhz and must always be equal to or less than this value.


The Hypertransport frequency = FSB x LDT ratio.

Default values would be, 200Mhz x 5. (= 1000Mhz)


If you overclock the FSB to 202Mhz, what would happen to the Hypertransport frequency?


202 x 5 = 1010Mhz.

So you need to do something to the LDT ratio.

Hint = lower it.


Any questions?

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the DFI NF4 guide here is the most comprehensive and detailed source of overclocking information for this series that exists... especially the ram section...


you should just start overclocking, make an effort, and when you get stuck, try something else... try to do it yourself and then start asking questions when you really can't figure out what to do next... you'll get further if you try as much as you can yourself ;)

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