Memory FAQ

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wow thanks for the info man. i've gone from a ram noob to a ram pro, as long as i can remember everything. :D I can't wait to start trying different tricks with my ram now. these stickies rule!
 
Originally posted by D14JEFF
a friend has a stick of 256 pc 2700 that is a simm(chips on one side only).can she add a 512 stick of pc 2700 dimm (chips on both sides and will she have issues if she does?ive seen issues using simm and dimm pc 133 ram but didnt know if the same problem exhist with ddr ram.she either has an asus or abit board.thanks.
Click to expand...

You've got your terms slightly off. You're talking about dual sided and single sided memory. A simm/dimm is different.

Memory banks: Where the memory goes (lol), and the way the chips are divided up in the addressing/hardware scheme. A full disclosure would take too much time.

SIMM: Single Inline Memory Module. These are the older type of memory, and had to be installed in PAIRS to make the bank full and functional (similar to the way RIMMs are now). Came in single sided and double sided. Haven't been used since the PII.

DIMM: Dual Inline Memory Module. These, by their design, have both halves of the bank on them. Thus, you only have to install them singly. They fill the entire bank on their own.

It's early, and I was out late... hope this makes sence.

As for your question, maybe, maybe not. I would buy the same kind of stick as you have installed (same brand/ratings), and it is almost guaranteed to work.
 
THUMBS UP to all that made this sitcky possible.... man I LOVE SITCKIES. Some really good an useful info here.

Anyone have any idea when DDR-II is comming?
 
Originally posted by zupadupa
THUMBS UP to all that made this sitcky possible.... man I LOVE SITCKIES. Some really good an useful info here.

Anyone have any idea when DDR-II is comming?
Click to expand...

It's here, sorta. You can buy the modules. Just mega expensive. And I don't think that there are any consumer boards that will take them, yet.
 
I currently have 4x512 PC3200 and according to this article having all slots filled dramatically decreases performance even to the point where 2x512 performs better realtime compared to fully populated 4x512. Just wondering if this article has any credence.
thanks.

http://firingsquad.com/hardware/building_gaming_opteron_2003_Part2/page14.asp

So would having simply 2x512 of the Mushkin 2-2-2 special be better than 4x512 of comparable RAM. The article also didn't state whether this was truly applicable with higherend apps when say around 2gb was being eaten up and having 1gb would cause swapping. hmmmm any ideas?
 
Originally posted by mayakindaguy
I currently have 4x512 PC3200 and according to this article having all slots filled dramatically decreases performance even to the point where 2x512 performs better realtime compared to fully populated 4x512. Just wondering if this article has any credence.
thanks.

http://firingsquad.com/hardware/building_gaming_opteron_2003_Part2/page14.asp

So would having simply 2x512 of the Mushkin 2-2-2 special be better than 4x512 of comparable RAM. The article also didn't state whether this was truly applicable with higherend apps when say around 2gb was being eaten up and having 1gb would cause swapping. hmmmm any ideas?
Click to expand...


Since you have four slots, why not 3x512?
 
With all of the conflicting info concerning how much ram is better. Does anyone have the definitive answer??????????


According to Anandtech, 4 populated slots give better performance than 2 for the P4.

http://www.anandtech.com/memory/showdoc.html?i=1839&p=8

Conclusion-
If you plan to run DDR400 as your base memory speed with an 800FSB processor, your best memory performance will clearly be with four matched double-sided DIMMs. Our tests, confirmed by Intel.

White Papers, show these configurations ranked from fastest to slowest performance on an Intel 875 Canterwood or 865 Springledale chipset motherboard.



FSB Overclocking with 1, 2, and 4 DIMMs

Since we have established that the best performance at DDR400 or above (1:1) is with four DIMMs, it is natural to ask whether there is a downside to running four DIMMs instead of two or even one DIMM.

http://www.anandtech.com/memory/showdoc.html?i=1839&p=7

Despite the slightly lower overclock possible with four DIMMs, the best 1:1 performance is still with four DIMMs. For example, DDR516 using four DIMMs out-performs DDR530 with two DIMMs –since the four DIMMs are about 7% to 10% higher in UNBuffered memory performance.


While four DIMMs do not overclock quite as well as two DIMMs on an 875/865 board, we confirmed that the added memory bandwidth more than makes up for the slightly lower overclock with four double-sided DIMMs.




The first page to this article "Searching for the Memory Holy Grail: Part 1.

http://www.anandtech.com/memory/showdoc.html?i=1839:confused:
 
good info, but either Anandtech has to be wrong or Firing Squad does. It is weird how their tests results came out contradictory and I believe that the issue as to whether 4 occupied slots decreases or increases performance has been an unresolved issue, as far as I'm concerned.

I also didn't quite understand why the Firingsquard article said they used XMS for their benchs and then at the last sentence of the first paragraph of the last page stated that 2.8 with better memory can outperform a 3.0 in some benchmarks. Then they go on to say that one should note that they weren't using bottom of the line memory;they were using Crucial. (Where or when Crucial memory came up in the test setup I don't remember reading prior to the Conclusion page).

The Firingsquad article also states that Intel deals with increased number of memory banks by slowing down the latency. I personally have not tested this increased latency theory and frankly do not know how, but I have never noticed a sudden change in the cpu-z readings when using all four banks. I no longer have 4x512 dimms and have switched down to 2x512 of lower latency Mushkin RAM to be ugraded as needed. Unfortunately, this does not allow for my own further personal testing on the matter and has left me without a definitive resolution to the issue at hand.

oooh, I'm a Limp Gawd now.:D The word limp does not quite sound so appealing I might add.
 
OK, you posted that firingsquad link in another thread, and this is just a cut and paste from my reply to the first post.

That article is an interesting read. Please notice this from the article, in bold. "extra memory can reduce system performance if it is unused."

Let me ask you this, do you think those benchies used 2GB? I doubt it. If they did, you would see a major performance increase in the 2GB vs 1GB because the latter setup would be swapping out to the page file.

Another thing, they are draw bad conclusions based on skewed testing. I wouldn't put too much faith in what your seeing. For example, they show you how ~bad~ it is to go from 1GB to 1.5GB on an AMD setup. Then they show you a memory bandwidth chart. Well, that mobo is DC capable, when they go to 1.5GB they are no longer in DC mode, if I recall correctly, and that will cut the memory bandwidth in 1/2, which it does... OK, so how does that affect performance? VERY LITTLE on that system. DC on an AMD setup yeilds ~3% increase. So the added bandwitdh isn't even used, so if it's cut in 1/2 who cares?
 
If this is the same FAQ as the one that was in the general forum a month ago, I have it saved in a word document if needed.
 
some of the FAQs got wacked in the switchover
Im rebuilding a few already
ChingChang thanx for the offer, B.B.S. should have a backup of it as well as the mod of General Hardware, but if for some reason he misplaced it
we'll be in touch :p
 
ahh ok, that would explain why some of the other stickies are missing the beginning part :)
 
Drisler, I have rebuilt your previous FAQ and stickied it - this thread will now be cut loose.


Thanks again for the excellent FAQ ;)
 
I personally dont know anything about DDR-2 other than what I've read and according to anandtech, DDR-2 sends twice as much prefetch (whatever that is) than DDR, and can equal the max bandwidth of DDR with half the frequency, much like the QDR you mentioned.

And I really wouldnt acclaim DDR2 just yet, I dont think its all that great of an investment as of right now.

Great FAQ btw, learned a few new tricks, but you forgot to mention (Or possibly I missed it) the whole amd64's (old socket) dependence on registered dimms. And explaining what registered ram is, its effect(affect?) on latency, and about ECC and its ability to correct 1-bit soft errors and flag 2-bit soft errors.

Oh yeah, maybe this is best fitted for a video card FAQ but you should explain about what AGP aperture is, many people with say 512mb of ram set this to as high as it goes (on most boards its 256mb) effectively giving 256mb more mb to their gfx and halfing their total ram for pretty much no performance gain.
 
Please use the new and improved FAQ stickied at the top of the forum
 
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