Bursting the Athlon 64 Memory bandwidth bubble

No_Style

So you bought yourself a new Athlon 64 CPU and want to pair it up with high quality components to extract maximum performance from your new PC? What memory should you buy?

It’s safe to say that PC2700 and older memory will not live up to the A64 challenge, starting from PC3200 your system will have all the memory bandwidth it needs to be blistering fast. Back in the glory days of the Athlon XP and Pentium 4 people pushed their FSB upwards to increase the memory bandwidth and this paid off quite well with an increase in performance of ~15% without the CPU being clocked higher!. Companies saw the need for memory rated higher than PC3200 and so the unofficial PC3500/3700/4000/4400/xxxx standards were born.

When Athlon 64 was released to the public many tried their tested tactics on this new platform, getting the HTT (A64’s equivalent to the FSB) as high as possible to gain extra performance. But A64 has an on-die memory controller,unlike the Athlon XP or P4, this controller allows you to run memory asynchronous to the HTT. Running memory async to the system bus is of course nothing new, but what is new, is the fact that performance between a system running memory async versus one running memory synchronous is virtually non-existent.

Sure there will be applications and benchmarks which will show you a difference favoring the synchronous 1:1 running system, but overall this increase in performance is nothing compared to the gains we so accustomed to have when doing the same on Athlon XP or P4.

So here today we are focusing on proving that Gamers don’t need expensive memory to get the most out of their Athlon 64 system.
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Read More/Source: Mad Shrimps

No_Style

After I posted this, I gave it a read and found it to be a very weak argument. They lacked any multimedia or application benchmarks. Nonetheless, people who're interested can give it a look.

Shaga

Worth reading, that's reason why I haven't tweak my memory bandwith to the maximum.

Zelig

They're correct, to a point... memory bandwidth doesn't seem to be the bottleneck in most dual-channel S939 situations, making increased CPU MHz much more important than increased memory bandwidth.

I'm currently running my S939 setup with single channel PC2500 ram... the performance hit from this compared to dual channel PC3200 ram is quite a bit higher than the performance benefit I get when running PC4000 ram or the like.

Also, with asynchronous mode not suffering a perforance hit, it gives more flexibiblty to people, since ram at 250 MHz with tight timings can perform pretty similarly to ram at 300 MHz with loose timings.

farkas

I wonder how the results would be with a set up like mine, s754 being single channel and all....

Matth

A huge difference between the memory tests, which clearly favoured a high clock, and the game tests, which tended to give most of the advantage from the lower latency.

2.5-3-3-X is slow? - good grief, what does that make the 3-3-3-8 on my Intel?
And I thought the Intel CPU's deep pipelines and HT placed a greater reliance on memory speed than the more nimble AMD - mind you, this is the 2Mb cached 640, so maybe slow RAM doesn't hurt it so badly - crappy OEM BIOS, so I can't even OC the RAM

Zelig

Matth: Intel rigs typically have more reliance on memory speed, while AMD has more reliance on tighter timings.