yeah, the AMD K8 CPU's can talk to RAM directly. Intel's have to talk to the motherboard's memory controller which then talk to RAM.
there's not much difference in RAM communication between an Intel with DDR2 and an AMD K8 with DDR1
the AMD K8 can communicate to RAM directly. the DDR2 RAM is faster, but Intel's CPU's have to talk to the memory controller on the motherboard which then talks to RAM.
when socket M2 comes out, CPU's in socket M2 will be able to use DDR2 RAM, and will communicate with RAM a lot faster than Intel's.
AMD spent a bit more time on dual core CPU's, and have really got it right. although it often does depend on the programs run whether you will see a performance gain. that applies to both Intel and AMD dual core CPU's
anyway, instead of Asus's A8N, I would recommend a DFI NF4 SLI-DR, which is less expensive and better than the Asus board. there's heaps of support for DFI boards at www.dfi-street.com
anyway, I would recommend:
if you can, get an Opteron 165 dual core.
essentially, they are exactly the same as the Athlon 64 X2's, but with a different name.
the 165 is 1.8GHZ against the 2.2GHZ 4400+, but still has the 2x1MB L2 cache you won't find in any lower end Athlon 64 X2.
having the same core as the X2's, they will be able to get similar speeds through overclocking.
2x512MB G.Skill RAM with Samsung TCCD's
G.Skill's RAM with Samsung TCCD's will clock well, and you should be able to get it to at least DDR500.
motherboard: DFI Nf4 Ultra-D
this board is the best for overclocking.
using that motherboard, CPU and RAM, you should be able to get around 2.6GHZ and at least DDR500.
I'll quote myself from a previous thread, so you can get an idea of overclocking:
originally posted by apokalipse
a CPU communicates to RAM at a certain speed, normally 200MHZ
DDR400 actually runs at 200MHZ, but transfers twice the data per clock cycle of the older SDRAM, so people say it runs at 400MHZ
your CPU has a multiplier, which is a number, that multiplies the CPU-to-RAM communication speed (normally called the Front Side Bus, but Athlon 64's technically don't have one, I'll explain after) to get the core speed
basically, to overclock your CPU, you increase your Front Side Bus (FSB, or HTT in Athlon 64's)
just say you had a 3000+, it runs at 2GHZ (2000MHZ) with a multiplier of 10
you increase the FSB (or HTT) to 250MHZ and your CPU speed is 250x10=2500MHZ
because you are increasing the CPU-to-RAM speed, you also overclock your RAM when you do this. this means your CPU can communicate to your RAM faster.
so what people often do, is they find the core limit of their CPU. let's say it can't get past its stock speed of 2000MHZ, they can increase the FSB/HTT to 250MHZ and decrease their multiplier to 8, so that 250x8=2000MHZ
the core speed is not increased, however their CPU communicates to RAM faster, meaning your system can be faster overall when parts need data from RAM (even if not the CPU itself, which is very often)
typically, when a CPU wants to communicate to RAM, it actually communicates through a memory controller chip (MCC) which is normally on the motherboard. the CPU itself does not normally 'know' how to talk to RAM. it is the link between the CPU and MCC which is called the FSB.
because the CPU has to talk to the MCC, it creates a bottleneck.
when AMD designed their K8 CPU's (Athlon 64's, Opterons, Semprons) they put the memory controller on the CPU itself. the MCC being just next to the CPU, not through the motherboard, means it can communicate much faster to RAM
because of this, there is no real need for a 'bus' to communicate with the MCC, it communicates almost directly to memory. AMD called the link between K8's and RAM "HyperTransporT" or HTT (don't confuse it with HT, which is Intel's HyperThreading)
anyway, the Opteron 165 has a core speed of 200 x 9 = 1800MHZ
the RAM at DDR500 will give you a core speed of 250 x 9 = 2250MHZ
the RAM I suggested should be able to reach DDR600 (300MHZ) with loose timings, which would make a core speed of 300 x 9 = 2700MHZ.
if your RAM can't reach 300MHZ, you can use a memory divider to make the HTT run at 300MHZ (or as high as it will go) and the RAM run at a lower speed, so you can still get a faster core speed.
also, for overclocking, a PSU is also important. a bad PSU can output irregular voltages and cause crashing, especially on a CPU that's overclocked.
plus, a lot of cheaper PSU's don't actually rate what they can constantly output, only their peak.
so you'll want a good PSU to power it all. I'd recommend an OCZ, Antec, or Thermaltake.
that's one of the best PSU's, which is really stable. it's peak output is 620W and can constantly output 520W.