Memory, lets talk about it from the new page. My view is initially based on SiSoft Sandra benchmarks.

1. Tests via ALU show lower results than tests via FPU for all memory types (but for a start I mean only SDRAMs). FPU uses 64-bit data ('double float' type) or 32-bit data ('float' type) while ALU uses 32-bit (long integer), 16-bit (integer) and 8-bit (short integer) data. Memory benchmarks will be the same if test uses only 32-bit binary instructions for ALU part regardless of what it uses for FPU part, or if test uses only 32-bit unary instructions for both ALU and FPU parts, because memory (SDRAM) is 64-bit wide, in the first case an entire block will be equally useful for FPU and ALU (if operands of binary instructions placed continuously), in the second case a block will be "half-useful" again equally. But the test actually doesn't work this way. It utilizes different methods. FPU data is mostly larger and less sensible for erratic accesses. ALU data, especially used by unary operations, requires more linearity but it doesn't get it always.

Furthermore, SiSoft Sandra uses STREAM test optimized for streams as you guess. Real memory performance is lower, because real programs are much more erratic and they use for many logical evaluations relatively small 16-bit and 8-bit values. Only precise float evaluations are performed with the speed test shows.

2. DDR-RAM uses same 64-bit data path to move next 64-bits, but only next. From the view of transmission and connection construction it has double frequency, from the view of addressing scheme and performance it has double bit-width. Tests shows that FPU bandwidth is increased by half and ALU bandwidth is increased by quarter. I have rounded numbers to show only tendency. Only binary 64-bit instructions work on full speed of the memory, also particular linearity helps reach 150% of non-DDR speed. In the same time only rare continuous memory addressing increases utility of the "128-bit" memory.

Real programs benefit from main DDR-RAM a little, and I ensure you programmers try as they can. But probably there is a hidden potential somewhere, I don't know. As I suggested before DDR-RAM is very effective in the real-performance/price term for using by GPU.

3. PC800 systems have triple memory performance over PC133 systems. Dual RIMM subsystem has 64-bit addressing (including DDR technology) and 400 MHz FSB. Why it can't have 200% bonus? So it has. I will not talk about latency, because there are a lot of enthusiasts. In the light of this I don't want to quarrel with anyone. Otherwise I, as a reasonable debater, need details which Intel didn't print for public reading.

I think RD-RAM is best choice for using by CPU, and price isn't a matter if you want ultimate performance.


P.S. Probably my English is getting better, but I still use Word.

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Don't read style, read meaning.