Inexpensive DDR3 RAM is out

[traveler]

Another price plunge for DDR3 RAM.


$89 dollars for OCZ 2x1024 DDR3 dual channel kit.


OCZ Dual Channel 2048MB PC10600 DDR3 1333MHz Memory (2 x 1024MB) OCZ3G13332GK at CompUSA.com

[XJ.]

4GiB kits are still insanely expensive (IMHO).

[traveler]

Originally Posted by XJ.

4GiB kits are still insanely expensive (IMHO).

$178 for 4 gigs of DDR3 is expensive? Twice the data throughput at a smaller voltage?

[XJ.]

Well, I already use 4GiB PC2 8500. From what I've read, you really need PC3 12800 to make a DDR3 board sing - and those 4Gig kits are expensive.

[ctal]

Originally Posted by traveler

$178 for 4 gigs of DDR3 is expensive? Twice the data throughput at a smaller voltage?

The higher clock rate of DDR3 will typically be negated by longer latencies, as well as by the fact that memory performance is not all that critical a factor to system performance. See the recent thread "Memory Doesn't Matter": Memory Doesn't Matter!

If by "twice the throughput" you are referring to the 8-bit pre-fetch of DDR3 vs. the 4-bit prefetch of DDR2, that is all internal to the memory, and is based on its internal (higher speed) clock. Relative to the external memory clock, the benefit of pre-fetch is built into the DDR2 or DDR3 speed rating (i.e., DDR2-800; DDR3-1600 etc.). The 8-bit prefetch of DDR3 is the main reason that its latencies are longer than those of DDR2.

Regards,
-- Al

[traveler]

Right you are Buds.

"As long as clock speeds double together with the latencies, e.g. DDR2-800 at CL4 vs. DDR3-1600 at CL8, nothing really changes.

The performance benefit of switching from one memory generation to the next has never been spectacular, although the theoretical bandwidth has increased a lot. PC3200 memory (DDR400) has a gross throughput of 3.2 GB/s, DDR2-800 is called PC2-6400, equaling 6.4 GB/s, and DDR3-1600 equals PC3-12800 or 12.8 GB/s. Since desktop PCs typically run memory in two channels, the effective gross bandwidth is twice as high: 6.4 GB/s for dual channel DDR400, 12.8 GB/s for DDR2-800 and 25.6 GB/s for DDR3-1600 in two channels. Larger processor caches allow the transfer of more and more code directly into the processor, so fast memory is not as important as it used to be."


Equal performance basically lowers the electric bill with DDR3.

The inexpensive DDR3 higher latencies are the "equal" ones.

DDR3 at CAS7 and even CAS6 on a DDR3-1800 stick does cost a bit more.

[ctal]

Yes, as I said in the other thread it seems that the main technical criterion for selecting memory (aside from cost, size, and future-proofing considerations), is choosing parameters that will not limit fsb/cpu speeds, based on your overclocking targets. In other words, you choose your mobo and cpu, choose a target fsb rate based on how much you want to overclock and based on what others have found the mobo and cpu able to handle, look at what fsb:memory clock ratios the mobo can provide, and select a memory that can handle the corresponding memory clock rate (with some margin). Then trade off cost vs. latency vs. memory size among the memories that are left.

Regards,

-- Al