Memory not synching with FSB at 1:1 with 9.5 CPU multi.

I'm over-clocking my OCZ Platinum.

I've gotten it to 260Mhz at 3-3-3-5.

I've booted at 270Mhz but my CPU gives out at 2.7Ghz.

So I thought I would just step down to a 9.5 CPU multi.

However my memory seems to be at CPU/10 still.

Right now my CPU is 2613 and my mem is 261.3Mhz, with the FSB at 275 x 9.5.

What's going on here?

I thought mem speed worked off the FSB, not the CPU?

Hmmm...

Maybe it needs an integer multiple because it synched at 9.

CPU-Z says mem speed is CPU/9?

half multi's just round up to a whole number I thought.

Rattle said:

half multi's just round up to a whole number I thought.

Click to expand...

That's what it looks like, for the memory. But the CPU used the 9.5 multiplier.

Anyway...

Here's my overclock results.

Max over-clock (3-3-3-5) @ 2.6V is 270Mhz .

Everest Home Edition:

Before: 216Mhz (2-3-2-0) @ 2.6V
Read: 5964 MB/s
Write: 2391 MB/S
Latency: 48.4 ns

After: 270Mhz (3-3-3-5) @ 2.6V
Read: 6935 MB/s
Write: 2859 MB/s
Latency: 45.9 ns

My CPU isn't stable at 2.7Ghz, bootable but not prime95 FFT stable.

To test the memory I'm running Prime95 Blend test. I'm about 10 minutes in without an error.

A few questions?

What's the advantage of the faster timings over these with higher bandwidth?
Why can't I use a 9.5 CPU multi. Apparently, memory speed is CPU/10 when there is a non-integer CPU multiplier.

Edit: Wow my monitor shut off, like the computer crashed when I hit submit, but then turned back on real quick like a power surge.

Probably because of the CPU.

Oh and prime just off only 11 minutes in.

I can run 9*270 to check for stability. But that configuration isn't as fast as 260*10.

Oh, btw, it did not boot with the memory at 275Mhz.

I would need my memory stable running at 289Mhz to run my CPU at 2.6Ghz with the 9 multiplier. Is that possible? Even looser timings, over volt?

I rebooted and now running 265x10 1:1.

Try to get that config prime stable. I need to run mem test to check the ram.

Should I try going even looser on the timings? Get more bandwidth?

Hey, don't use half-multipliers with an athlon 64. It significantly reduces performance.

Quailane said:

Hey, don't use half-multipliers with an athlon 64. It significantly reduces performance.

Click to expand...

Thanks.

Do you know why it reduces performance?


Computer crashed about half hour into Prime95 with CPU temp peaking at 61C. Looks like I'll be running 2.6Ghz. This was at 1.59V BTW. I wouldn't want to run that high of a voltage anyway.

InfiniteThought said:

Thanks.

Do you know why it reduces performance?


Computer crashed about half hour into Prime95 with CPU temp peaking at 61C. Looks like I'll be running 2.6Ghz. This was at 1.59V BTW. I wouldn't want to run that high of a voltage anyway.

Click to expand...

I believe @ extremeoverclockers forum they recommend 1.6 w/ good cooling system. also your ram may need more voltage, about 2.9v.

ochungry said:

I believe @ extremeoverclockers forum they recommend 1.6 w/ good cooling system. also your ram may need more voltage, about 2.9v.

Click to expand...

I plan to add a second fan and another case exhaust fan, possibly using a wind tunnel out of the Sonic Tower. Right now I'm using only one fans, which means there is only signifigant air flow through half of my cooler. Temps should drop dramatically after adding more air flow. I should be able to get much better cooling performance out of my TTST then the Typhoon or XP-120/90c with better air flow. The TTST has the best conductivity of any heat sink I've seen tested, that's why I bought it.

Then again, this may not help my OC cause any. I think I've hit a brick wall on my CPU. But, maybe there's still more room to play with. I'm very happy with the system as it is now.

Most guys at or above 1.6 are on water anyway.

Should I try pushing the ram any faster? Looser timings, more voltage? I'm still fairly new to over clocking, what do I try next with my ram?

Having a great time though. Over clocking is almost addicting.

InfiniteThought said:

I thought mem speed worked off the FSB, not the CPU?

Click to expand...

Yes, memory freq is derived straight from CPU clock, not HTT (not exactly FSB).

Quailane said:

Hey, don't use half-multipliers with an athlon 64. It significantly reduces performance.

Click to expand...

Memory frequency - and bandwidth - have very small impact on A64's performance. There are no other effects other than slightly lowered memory frequency when using non-integer multipliers:

DRAM_frequency = CPU_frequency / ceil (CPU_multiplier / DRAM_frequency_divider).
Ceil: the smallest integral value no less than CPU_multiplier.

DRAM_frequency = 2565MHz / ceil (9.5 / 1:1)
DRAM_frequency = 2565MHz / 10
DRAM_frequency = 256.5MHz

10 x 261.3 you mentioned is better than 9.5 x 270. CPU clock is all that matters on A64 - if you'r not benching.

i thought usin .5 multi's forced you into running async.

I had enquired DFI and they told me that's a issue with AMD processor, they suggest use 9x, 8x, 7x... do not use half mutlipler. That's the engineer told me from DFI.

there are no such things as .5x multipliers with Athlon64, only integers. Any app that is telling you that you are using 9.5x is lying to you. As you've seen, using 0.5x multipliers makes the system round it up to the next integer. In your case, it would be 10x. Then your HTT and memory speed are taken from CPU speed/10.