Does opteron64 access RAM differently than athlon64

[ClockWork]

Using the same MB in both instances I had an athlon 3800 running at 2.45 GHZ with 1.47 volts and my RAM was at 217 or so and there were no issues rime stable and all.


Now with a opty 165 @270 with 1.37 volts and all other settings the same (other than FSB) I need to adjust my mem divider to 144 to run stable or even boot for that matter. I tried 187 and no boot.

Any insight would be appreciated.

[koei]

It would depend on the core. That 3800 should be a Venice whereas the Opteron is Toledo.

[Fhqwhgads6680]

What type of ram is it, running the 180 divider would put your ram at about 240ish which may be just too high for your ram...have you tried the 166 divider. Also do you have A64 tweaker? use that to find your rams sweet spot for timings. Also what mobo are you running and how much voltage? With this info I could give a little more specific adivce.

[ClockWork]

I'm using 2x 1gb of gigaram cas 2.5 ddr400

the dividers i gave you were not the divider but the actual timings

with the opty 165 WITH A FSB OF 300 and HT at 3 I can only run my ram at 150mhz whereas with the same MB and ram with my 3800 I could get my memory stable at 215 mhz.

Now the 3800 has a multiplier of 10 versus 9 for the 165 but mhz is mhz Why would my ram overclock fine with one chip yet not the other.


Could this be an issue other then the RAM


Thanks

[uOpt]

The speed at which RAM can be driven is determined by the quality of the memory controller in the idividual chip. While Opterons tend to have better quality silicon on average it is still a question of the individial chip.

[Charloz24]

I have the same problem as you with my TCCD and OPTY....

[ClockWork]

The thing is this with the opty 165 @ a 10% overclock I can run my 2GB of RAM at 210 mhz cas 2.5 1T

However when I overclock my opty to 2.7 I need to pull the memory divider down to 1/2 (150mhz) to run stable. (I also lower the HT to 3x to help ensure stability)

Even settings under the stock 200mhz like a divider yielding 180mhz RAM frequency will prevent my PC from even booting.

I understand the opty has an on die memeory controller but technically the divider locks the RAM frequncy; Therefore it should not matter whether my CPU is at 1.9 or 2.7 providing my end RAM frequency is the same.

The only other possible cause is that the MB an EVGA N4SLI does not like the higher FSB frequency. Could FSB frequency on a MB affect RAM stability even if RAM frequency is divided to remain the same.

I thought I read a post that Opty's accessed memeory differently than Athlons which is why I thought maybe that could be an issue. Maybe I should try a different MB like a DFI or Asus instead of trying better RAM

Again any insight would be much appreciated

BTW the stepping on my OPTY 165 is ccbwe0546mpmw. So far I get a nice 2.7 overclock with just 1.4 volts

[Fhqwhgads6680]

Try uping the ldt volts up .1 this sometimes helps stabilize the mem controller. Also since it does have the 9x multi, running high htt sometimes cause mem controllers or mobo chipsets to flake out.

Remember isolate and consolidate. If you have a friend with decent ram that can run certain speeds then test it on both the opty and the x2. if it is having similar issues try it in a different mobo. I know that the dfi's have no problem running > 300 htt but there are quite a few 939 mobos that do...this could be the problem as well.

Also as far as if the access it in a different way the answer is no....however optys DO have an extra htt lane (I believe) so also make sure you lower the htt to x3

GL let us know if you figure it out!

[largon]

However when I overclock my opty to 2.7 I need to pull the memory divider down to 1/2 (150mhz) to run stable.

- - technically the divider locks the RAM frequncy; Therefore it should not matter whether my CPU is at 1.9 or 2.7Divider doesn't lock the memory frequency.

On K8 architecture CPU freq is the thing that dictates memory frequency. What a divider does is this: it divides the CPU freq with an integer determined by the divider setting.
If your cpu multiplier is 10 memory dividers go like this:
"200"=10
"183"=11
"166"=12
"150"=13
and so on.

with the opty 165 WITH A FSB OF 300 and HT at 3 I can only run my ram at 150mhz whereas with the same MB and ram with my 3800 I could get my memory stable at 215 mhz.You'r Opteron at 2700MHz with the divider "150" -> your RAM freq is 2700MHz / 13 = 207.7MHz