dual channel

I was considering buying the amd athlon 64 but then i couldn't find a mobo with dual channel to take full opertunity of the f.s.b. Does any one know if there are current mobos with dual channel for the athlon 64 or if there will be with in the next year. I know there is dual channel for the fx-51 but i don't have 700 dollars just for the processor

You won't find a dual channel motherboard for the A64. The memory controller is integrated into the CPU, so the CPU determines whether or not you have dual-channel memory. The whole advantge of the AFX is dual-channel memory.

The dual channel is not different from single channel performance-wise. There is only about 1-2% max.

how is it that there isn't a dual channel advantage. it runs at twice the speed which means it keeps up with the f.s.b. doesn't it? can you explain your logic

There is already a limited theoretical bandwidth of the fsb. Only so much data can go through the link to the processor, and that equals the theoretical limit of ddr400 ram. It does quite get up there, but it is close. Dual channel just ekes out the bit that single channel missed.

I read in a post somewhere that A64 FX's support dual channel, but Im not positive. ....and I dont know if you'd want to pay that much for one.

Dual-channel operates like dual processors -- two transfer pipelines at the same time. Only really effective with Hyperthreading enabled (Intel). The FX chips have Hypertransport, which is similar, and thus gets the same performance benefits. There's no point to have dual channel on anything that doesn't benefit from the technology. Depending on the application or applications (as it is only truely effective in a multitasking environment), you could get up to a 30% increase. In general, it is about a 5% increase overall.

-Frank

a c i d.f l y said:

Dual-channel operates like dual processors -- two transfer pipelines at the same time. Only really effective with Hyperthreading enabled (Intel). The FX chips have Hypertransport, which is similar, and thus gets the same performance benefits. There's no point to have dual channel on anything that doesn't benefit from the technology. Depending on the application or applications (as it is only truely effective in a multitasking environment), you could get up to a 30% increase. In general, it is about a 5% increase overall.

-Frank

Click to expand...

This is not entirely correct. Dual channel RAM is more like a RAID0 array (although not very much, really), data is spread accross both channels, so it can be pulled from both at the same time, increasing performance in many situations. In a perfect world, this would double the bandwidth to the RAM. Doubling bandwidth would not, however double CPU performance.
(If someone feels like posting a better explination, please do so, I'm not so good at explaning things to people)

The P4 takes advantage of dual channel memory because it has a high enough bus speed that it can take advantage of theincrease in bandwidth from dual channel ram. An Athlon XP eith a 200MHz (400 effective) FSB has the same theoretical bandwidth as a single stick of PC3200 RAM. The AFX can take advantage of dual-channel ram because the memory controller is integrated into the CPU, removing the FSB bottleneck.

HyperTransport is not similar to Hyperthreading. Hypertransport is a high speed serial bus for chip-to-chip interconnects, while hyperthreading is a marketing name for intel's implimentation of SMT (Symmetric Multi Threading).

the new 939 cpu will have dual mem but u will need a new mobo they r going to haVE 512 cache just like a64 3000+.