(sort-of newbie) what is this new-fangled tech.?

[onlinejb]

I haven't built a computer since 1997, and technology has changed waaay too much. It's like I was just fragged and reborn six years in the future. I'm reading the articles on this site, and thinking uhhhh...wuzzat, whatcha-say???? It seems that reading product reviews doesn't help-I need literature that explains the *technology*, not the product! Here's just a sample of the questions I'm trying to answer:

What is the difference between FSB ratings (like FSB800) and the memory ratings (like PC2100 and such)? What memory speeds work with what FSB speeds? What does "quad-pumped" mean?

If someone can either answer these questions or direct me to a site that actually explains it, I would appreciate it!

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

 

[alc101ma]

Intel processors are quad pumped. This means the newest P4's really have a 200MHz FSB quad pumped to 800MHz. The newest Athlons also have a 200MHz FSB but AMD cpus are only dual pumped to 400MHz. You don't really have to worry about how/why the bus pumping works. The only important part is that the FSB is first set as 100, 133, 166, 200... and THEN pumped for the final FSB. For instance if you were overclocking your 133MHz FSB Athlon to 140MHz... you'd end up with a 280MHz FSB in the end. The memory part is kinda tricky. Memory can be classified according to both speed in MHz and also bandwidth (in MHz/s I think). This change from speed to bandwidth started with DDR, I think, as a marketing ploy to emphasize the increased bandwidth. For instance, what we call PC2100 (refering to the bandwidth) can also be called DDR266 (refering to the bus speed). I hope this helps.

<P ID="edit"><FONT SIZE=-1><EM>Edited by alc101ma on 07/20/03 01:55 AM.</EM></FONT></P>

 

[pIII_Man]

Plz! for crashmans sake (and i do see his reasons) do not call it pumped...it is Quad data rate or Dual data rate...basically what is happening is the signal send multiple bits of data each clock cycle.

Here is my crash course in memory...

to find memory speed from a bandwith number

bandwith/8 = speed

pc3200: 3200/8 = 400mhz(that is the ddr speed) the real memory speed is 200mhz but manufacturers play on the double data rate to make the memory seem more special.

and the inverese to above
mhz x 8 = bandwith

333mhz x 8 = 2700 (aproxamitly...the reason i gave that example is to remind you that companies round to make their memory sound better).

Have fun with your new system...will woop any pentium pro system you have made previously...but is no match for my overclocked 286 :tongue:


There is no smell better than fried silicon

 

[onlinejb]

If your FSB is 533MHz or 800MHz how fast should the RAM be?

 

[pIII_Man]

since the p4 uses a quad data rate bus

800mhz/4= 200mhz thus pc3200 ddr ram

533mhz/4=133mhz thus pc2100 ddr ram or pc1066 RDram

There is no smell better than fried silicon

 

[Crashman]

It depends on the RAM and the platform. RDRAM has come and gone since 1997, and it ran at very high speeds, but on a very narrow data path. For common i850E chipset board as an example, a "533" bus would run with "PC1066". In reality the CPU bus was 133MHz and the PC1066 was 533MHz using DDR technology (for the PC1066 name) on a narrow 16-bit channel. In order to make up for the narrow channel, it was ran in pairs which were parallel, for 32-bits of memory bandwidth at 533MHz. Anyway...

We're back to SDRAM now. DDR SDRAM. Ideally, you like your memory bus to be the same speed as your CPU bus, so the memory controller doesn't have to worry about conversion. That makes the QDR800 CPU bus and DDR400 memory bus a match at 200MHz. But to match bandwidth between the two, DDR chipsets now support parallel operation for a pair of modules, called Dual Channel.

The CPU bus and DDR SDRAM module are both 64-bits, so running two DDR modules parallel makes the RAM bus 128-bits. This makes the transition from the QDR bus of the CPU to the DDR bus of the RAM...bandwidth matching.

Older single channel chipsets that used DDR SDRAM had a problem with Intel's high bandwidth CPU bus, because of the QDR to DDR conversion. In single channel mode, a QDR800 bus would have twice as much bandwidth as that single PC3200 module. So going back to QDR400 busses of early P4's, the ideal DDR SDRAM memory would have been single channel PC3200. It didn't exist yet. Which is why Rambus was so popular back then.

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