Definitive answers to overclocking A64

[Soul Rider]

There are many different questions and theories pertaining to getting the best results from overclocking an A64 chip - should i drop the LT multiplier? Should I use memory dividers? and many other questions.

This article tells you all exactly how it works and what effects the various aspects of changing LDT multipliers, memory dividers and FSB settings actually gives you.

If you've ever been curious as to what is important to get an good A64 overclock, this is for you...

http://www.neoseeker.com/Articles/Hardware/Guides/athlon64oc/

Apologies if it's already been posted, but i think it is very informative and i haven't seen it here before.

 

[Soul Rider]

It has been posted before, but it's a good informative read, so I don't think anyone will complain about a repost.

Also, after the number of articles and the like stating how the A64 prefer tight memory timings, I've been spending a few hours benchmarking memory at various timings, and the onlytimings that seem to make a noticable difference is the Trp, which can't be changed much anyway. So I'm now going to relax the timings and max out frequency

Keep us updated squidge on how this goes. I'm personnally now rethinking the need for PC4000 RAM. Although there is a benefit to overclocking the RAM, the use of dividers doesn't hold it back too much. I might go for 2GB of cheaper RAM, rather than 1GB of expensive.

 

[Soul Rider]

The only thing missing form the article is how memory timings affect the speed in several programs.

True, are you volunteering to test this out Dutch Guy?

 

[Soul Rider]

Just summing up so far -

Squidge discovered a loss of 400MB/Sec when he slackened his timings, but managed over a 1000MB/Sec by getting the higher frequency the looser timings allowed, showing that sacrificing timings for the frequency resulted in an overall gain on the memory bandwidth.

mj3zero discovered that changing his 2.7Ghz clock from 10*270 to 9*300 and thus increasing his memory speed resulted in a SuperPi bench imporovement of 1 sec.

This is great guys, this extra research added to the tests in the OP really give us an insight into what produces the best overclock possible.

 

[Soul Rider]

^ so its a totally mixed bag all around then!

What?

They are supporting the same evidence. Loosening timings to improve frequency means better results in squidge's example, and mj3zero found the extra memory bandwidth from the higher bus increased speed.

So both say increased memory frequency is better for the system, how is that a mixed bag?

Two different tests, same results..

 

[Soul Rider]

Sorry for the threadromancy, but it's only a couple of days and i fell this fits in with this topic...

Lots of people have had problems running their memory at 1t with these processors. Someone in the forums, forgot name and thread , was unable to run at 1t timings, so had them relaxed to 2t, however....

The lowered the burst rate from 4 - 8 and when they tried to tighten the memory to run at 1t it was stable.

Now here's the question i would like to find the answer to...

Changing the burst rate down to 8 decreases memory performance, increasing to 1t increases performance.

Is there anyone out there who could try testing this, 8 bursts @ 1t, then 4 bursts @ 2t, then 8 bursts @ 2t. Keeping all other memory timings the same.

Can we see how much of a decrease in performance is brought on by 8 burst timing, and how much of an increase is brought on by 1t. This way we can see whether this is a worthwhile way of getting memory running @1t.

I would do it but my current memory can't run @1t.