Pentium 4/Northwood and DDR SDRAM

[Wingznut]

Dual channel RDRAM does sound very nice... But does that mean all the people who bashed RDRAM for requiring pairs of sticks of RAM won't buy an nForce? Yeah, I didn't think so.

But personally, I don't think the nForce board will retail for less than $179. No matter what that ever reliable source, theregister, says.

 

[NFS4]

<< Dual channel RDRAM does sound very nice... But does that mean all the people who bashed RDRAM for requiring pairs of sticks of RAM won't buy an nForce? Yeah, I didn't think so. >>


1) Don't you mean Dual channel DDR SDRAM?
2) You don't HAVE to install DDR modules in pairs. It's not a necessity.

 

[RedBeard0531]

<< But does that mean all the people who bashed RDRAM for requiring pairs of sticks of RAM won't buy an nForce? >>


The nForce doesn't require matched pairs of sticks. Since it has 2 seporate memory controlers, it can have only one stick or 2 sticks of differant sizes and *possably* speeds. Although for best performance, they should be installed in matched pairs.

Edit: I need to learn to type, NFS4 beat me to it

I wonder tho, if I put 1 256meg stick in bank1 and two 128's in bank2, would that be the same as 1 256 in each bank?

 

[Wingznut]

Yep, I meant DDR RAM. (Man, I'm not doing so good tonight. *sigh* )

And I know it doesn't &quot;require&quot; pairs, but that's obviously the best solution.

 

[ElFenix]

redbeard - i think the same &quot;rdram optimizations&quot; that are already in place with P4 - mainly the hardware prefetch so that data is in L2 cache as much as possible, would not need to be modified for DDR use. the p4 works best when the data is in L2 so that it &quot;hides&quot; any possible rdram latency issues. although i once heard a tale that intel's rdram controller implementation isn't a particularly good one (some rambus guy blaming i820 for the p3's miraculous performance with rdram). if this is true, the i845 might be close to i850 in terms of bandwidth, since we know that intel's sdram controllers are excellent.

as for the layer thing, according to the 1.8GHz p4 review, 6 layer boards are $10 - $15 more expensive than 4 layer boards. i don't know about anyone else, but i think that i'd be willing to pay an extra $35 for an nforce 420 vs 220 board.

 

[Adul]

Now many of youare assuming that pc2100 DDR-Sdram will be used. While it is the case of the via chipset, I do not think intels own DDR chipset will run memory asyncronously. Unless someone alse has heard otherwise, intels chipset will offer the same bandwidth has the RDRAM counter part.

 

[NFS4]

<< Now many of youare assuming that pc2100 DDR-Sdram will be used. While it is the case of the via chipset, I do not think intels own DDR chipset will run memory asyncronously. Unless someone alse has heard otherwise, intels chipset will offer the same bandwidth has the RDRAM counter part. >>


Well, the SDRAM chipset uses PC133 memory, not PC100. The Pentium 4 uses a 100MHz quad-pumped bus. So given those facts, I would assume that the memory is already running asyncronously.

So if the PC133 chipset does it, and PC2100 is the counterpart to PC133, why not for the DDR version of the i845? Besides, PC1600 memory is not all that popular anymore.

 

[Adul]

Good point nfs4, I wasn't thinking about the sdram counter part. But still one has to think if the deal with rambus has anything to say about how fast the DDR memory can be for intel's chipset. They do not want to make rdram look bad now do they.

 

[Noriaki]

Well the i850 is Async'd

Ignoring bus-width and DDR/QDR, the P4's FSB is 100Mhz and it's Memory clock is 400Mhz.