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2100 vs 2700 Please help!

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Feb 8, 2002
Land O Lakes,FL Orig from Tampa, FL!
Ok everyone please inform me, Ii am running a 1.6 northwood (not Oc'd yet) with 512 2100 single, will I see a big difference between 2100 and 2700 or not?? I was told yes and no by many different people, and most the reads i saw said yes, but it seems to me that if im going to OC the fsb it wont matter, Am I crazy or what??

Mike A
i'm a little new with memory info but as far as i know the only difference between pc2100 and pc2700 is the max rated fsb it can run at. if you run pc2700 ram at pc2100 fsb speeds, you will see little if any improvement.
Mlakrid is correct. The benefit of PC2700 is in its overclockability. If you are thinking of Kingmax PC2700, then go for it. Make sure that the chips are 5ns, and not higher. Higher than 5ns means that the chips are actually just overclocked PC2400 or lower.

You're running a Petium 4 so unless you're running some serious cooling, you won't ever run at the speed of at 2700 speeds, which is designed to run at 166mhz fsb.(I'm not all that up to date with P4's, so if your P4 runs at 133/533 fsb, it a lot easier to get that high, but still not easy.) Crucial make great pc2100 that will easily do 150mhz with good timmings(with a +.2v increase), even higher if you raise the volts higher.

Another thing you got to look at is what ram timmings you can run at. The faster the timings the bigger the bandwidth, but more unstable at higher fsb speeds. So good pc2700 will run at faster timmings at 150mhz compared to pc2100(both at default voltage)

So it all boils down on what fsb you're aiming at, and if you run pc2100 and 2700 at the same speed and timmings, the bandwith will be almost exactly the same.
P4 DDR boards run on a 100Mhz bus. So you have 100Mhz x 2.66 (memory multiplier) = 266Mhz in a basic setup. When you OC and raise your FSB, you also raise your memory speed by a factor of 2.66, not 2! (Exception: there's all kinds of divider schemes and points on the various boards so YMMV)

Right now I'm running an FSB of 128 which gives me a memory speed of (128 x 2.66) 340Mhz. I can run as high as 350Mhz on my board (an Asus P4B266) until the 1:1 divider kicks in, then I'd have to be able to get an FSB of over 175 (fat chance w/o watercooling, even on a P4 Northwood) before my RAM speed would get back over 350Mhz.

To make a long story short, it's easy to get PC2700 (that's 333Mhz) speeds on a P4 if your board has the right kind of dividers.
Personally I'll go with Pc2700, preferably CorsairXMS, coz rated for Cas2, and not Cas2.5, and this improve the mem bandwidth, and more, just build in HeatSpreader ;)
PC2700 without a doubt. Even if you MoBo can't reach that high your sure to run with the the most aggresive timings. A single stick of 512Mb is not such a good choice for O/Cing so going with 2 X 256Mb would be a better choice.
sonny said:
A single stick of 512Mb is not such a good choice for O/Cing so going with 2 X 256Mb would be a better choice.

Why is that? I always thought less sticks is better. Explain please.
Yes, it's true that less sticks are better to gain higher Fsb, and onestly I don't know which is the technical reason, but probably depends by the fact that the most part of the chips manufacture are for mem modules of 256Mb, so I suppose that the production is more 'sharpen', or better, accuarate ;)
Ralf Hutter

To give you a better Idea, I have in my system at this moment:
ASUS P4B 266, P1.6Ghz Northwood not Oc'd yet, a 64 Mb geforce2 video board, 1 stick of PC2100 ram (512MB) thats why I was asking the question I did, a Deluxe midtower case with a 350W P/S, SB 5.1 sound card ATA-100 20GB Maxtor HD (I didnt like this one I have heard mixed reviews, trying to get them to take it back) and Im running XP I just got done building my first water block on the Mill at work, I have to buy a Dremel tool this weekend to polish the aluminum in the block, then Ill enter this baby in the wter-cooling competition just to see how it does. ANY and all advice anyone has about any of my gear please send away, I check the forums 2 a day or so. THanks

Mike A
Well, but don't disperate ;) every module born different from the others, and only after some test you'll know how far it can go, even if generally the 256Mb are better.

Which brand is your module mlakrid?
nikhsub1 said:
Why is that? I always thought less sticks is better. Explain please.
Everybody agrees that the less sticks the better right? Right, because of a capacitance problem. Having more sticks increases this problem. Just like what Mushkin says;
Unregistered SDRAM limits the maximum frequency you can run SDRAM reliably with out having to introduce latencies, the reason is that more chips connected to the memory bus the greater the capacitance load.

Higher capacitance loads require more current to drive the signals to the valid voltage levels. So for the best memory bus performance, the less DIMMS the better (we've seen numerous examples of this, where a board will run stable with one DIMM, but lose stability once more DIMMs are added). Of course, less memory may result in better “benchmark performance” for your memory subsystem, but if you don't have enough memory for your applications then there will be an even bigger performance hit on the performance of your whole system than just running your memory at CAS 3.

So if you need more and better memory performance it’s best to select a DIMM with the highest memory density supported by your motherboard's chipset (check your motherboard manual). This results in less chips connected to the memory bus, therefore your memory bus will see less capacitance load.
BUT how long did it take manufacturers to release a reliable 512Mb stick that would run at CAS 2 & the most agressive timings on all other areas? The density in one stick of 512Mb creates a greater amount of capacitance then 2 X 256Mb I believe. No hard facts to back that up just some experirence & practical thinking. It would also be easier to troubleshoot & the flexibility of being able to find out which bank/stick can go higher & if they were all in just one stick then a single module can limit your FSB.

I found out about the problems with single 512Mb sticks from playing with a bunch of set ups in the computer shop I frequent. With the realease of faster rated memory in newer PCB layouts this will probably not be an issue anymore.
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I'll find out about any possible problems with running 2 sticks of 512Mb RAM because I just bought a second stick of the Corsair 512Mb PC2700 XMS RAM.

The first stick I bought the other day runs great at 340Mhz so I figured "hell, what's another $205, I need a gig of DDR333 RAM in my box" so I bought another stick.

I'm running Memtest86 on it right now, I'll run it for 10-15 hrs or so and see how it holds up.
Ram type

To be honest Im not sure, probably a generic, I dont think i specified a name brand when I bought the rest of my gear.
If so, its no big deal Ill get my best friend to buy this and take a $30 hit or so, it'll be beneficial for both him and myself. Ill get the better ram, and he gets a brand new 2100 512MB stick. So I lose the cost of sending the stick back, waiting blah blah.. You know how it goes, specifiy or get what they send you. My mistake not theirs.

Mike A
Ran Memtest 86, looped for 11 hrs on my 2 x 512Mb sticks of Corsair PC2700 RAM @ 340Mhz, CAS2, 2.5v the other night. Ran perfect with zero errors. Getting Sandra mem scores right at 2600. I certainly haven't found any issues with these 512Mb sticks yet.
Re: Ram type

mlakrid said:
To be honest Im not sure, probably a generic...
Mike A
Well, take a look to the code written on the mem module chips, it can help us to understand the manufacturer, and in anyway you'll know how far it can go, only rising the Fsb ;)
memory module

I looked at the Invoice this morning and if memory sevres me right it has no name brand but says:
MMPC2 whatever the hell that means. Il check the chip itself tonight when I get home. Thanks for the info everyone.
I've read that its best to stay away from 2700 until there are standards for it. According to the article, they had experienced problems with them. So based on that, I recommend wait until the group that writes the standards makes the 2700 standard