ebay RAM Guide info- is this true?

[ahhaa]

I found this on one of those new buyers guides on ebay:

DDR-400 for example will only have a frequency of 200 not 400 if your system is not set up properly, most systems require you to have 2 modules in before your system will operate at DDR. Your system will not operate DDR with 1 or 3 modules in it.

So you could actually slow your machine by improperly adding memory?

& boy, are there some crooks on there... one picture showed a memory stick with the 'warenty' labelling sticker mis-spelled!

[kschang]

It's BS, based on incomplete understanding of the system.

DDR is double data rate. Instead of transfering memory once per clock cycle, it transfers memory TWICE per clock cycle. The amount of memory has nothing to do with it. It's a part of mainboard's design, nothing more, nothing less.

As for the rumor that you will slow your computer down... That's mixing up "dual channel" with DDR. NVIDIA started the idea of "dual channel" on their nForce mainboards. Basically, the mainboard has two memory access channels instead of one, and can access TWO separate banks of memory per clock cycle... If you got identical memory in both slots. In a way, it's similar to "interleaved memory" back in the 386 days, but I doubt many of you remember that far back. The idea of dual channel is you get double the memory bandwidth. However, the actual gain is more like 10-15%, since most memory access use contiguous memory blocks, and dual channel doesn't help that.

[ahhaa]

I guessed I would have heard of this if it was true.

So there is no speed (or other relevant to video editing) difference between having one 1 gig stick, or having two 512 meg sticks?

[Cobra]

Depends - something like encoding isn't too memory-intensive, so I wouldn't think it would make much difference. However, using some packages involving visual effects and real-time editing could be very memory-intensive and so it would make a bit of difference.

[ROF]

I thought everything you did on a computer was memory involving? Everything no matter how simplistic it is passes through memory. The faster the data rate of the transfer the faster the process completes. Even typing this requires the computer to utilize RAM.

That being said, DDR when used in dual channel mode is much faster than adding DDR. Dual Channel not only effects the RAM but it also increases the efficency of the FSB. As everyone knows, the faster the FSB the faster the data transfer and the less chance for a bottleneck. I do not build systems without using dual channel. It makes no sense not to utilize something so vital to everyday computing.

[Cobra]

Just about everything on a computer does involve the RAM, but it is the rate at which it needs data that gives systems with more bandwidth the edge. Video encoding might need a few megabytes a second, which is nothing. A game might need a gigabyte a second, which is a fair bit.

[ROF]

Just about everything on a computer does involve the RAM, but it is the rate at which it needs data that gives systems with more bandwidth the edge. Video encoding might need a few megabytes a second, which is nothing. A game might need a gigabyte a second, which is a fair bit.

But the amount is irrelevant when your discuss 2 x 512 or 1x1024. They are the same thing. Dual Channeled RAM no matter if it is processing a single character or 1000 lines of code will be much faster than it's single channel counterpart calculating the same amount of information. The point being, since your Motherboard/CPU supports dual channel RAM and the relative price for 1 x 1024 and 2 x 512 is the same it makes zero sense to buy into single channel RAM when your machine is capable of dual channel.

[Cobra]

Both single-channel and dual-channel modules are more than capable of delivering a few megabytes of data over a second. That is all that is requested of them - they are not transmitting at full speed. Dual-channel is advantageous when you must deliver more data than a single-controller can cope with in that one second. I might be missing something obvious here - where am I going wrong?

[ROF]

In a computer system if something can do something twice as fast with the same accuracy is it not better? This is where I believe you to be incorrect. Dual/Single Channel does not care about the size chunk of the overall data it processes. It's only concern is I/O. Dual channel can accept data faster and spit it out faste. In the process the FSB of the processor socket that supports dual channel is also increased in efficency and can process more data in a faster rate of time.

You are correct that when larger chunks are handled, dual channel is faster. Where you are incorrect is that smaller chunks are not processed quicker. Overall speed doesn't change. Since most video editing/encoding requires large amounts of data to be processed, a dual channeled system is preferred over single channel. No matter the size of the project.

[TBoneit]

MY take on this rubbish!

I found this on one of those new buyers guides on ebay:

DDR-400 for example will only have a frequency of 200 not 400 if your system is not set up properly,

Me: Wrong depends on the FSb of the processor.

most systems require you to have 2 modules in before your system will operate at DDR.

Me: Wrong again, one two three or four depending on the motherboard, DDR is DDr

Your system will not operate DDR with 1 or 3 modules in it.

Me: So Wrong

So you could actually slow your machine by improperly adding memory?

Me: Yes you could slow it down if it was configured from the factory as Dual Channel mode, And you add one piece of memory then you will have more memory but will drop out of dual channel mode and slow down memory accesses.


& boy, are there some crooks on there... one picture showed a memory stick with the 'warenty' labelling sticker mis-spelled!

Crook on E-Bay? Shock, Horror, Gasp!

BTW Normal to see Dual Channel mode on P4 with 800FSb on better Systems/Motherboards.

OTOH When you see computers being sold without enough memory when new, well.

[oldandinthe way]

The following statement appears in my Intel motherboard manual

Dual Channel Interleaved Mode - This mode offers the highest throughput for real world applications. Dual Channel Mode is enabled when the installed memory capacity of both DIMM channels are equal. On my motherboard, 2 256m modules run faster than 1 512m module.

[otpw1]

Cracked open a 775 motherboard manual. It agrees with oldandintheway.

Edit An amd motherboard manual says the same thing.

[ahhaa]

This is interesting, thanks guys!
While I can't afford to build a top-of-the-line-today machine, I can afford a top-of-the-line-'yesterday' machine; if you know what I mean...

I found a good review of my mobo, and asked the guy his opinion on RAM- thought you guys would like to see it:

The trouble with 1GB RAM modules is that they are usually
double-stacked, and most boards of the KT4VL era can only use RAM chips
with a certain number of chips. I don't remember how many -- 16 maybe.
Aside from that, there are address space limitations in 32-bit x86
motherboards that prevent actually using all 3GB. You end up with more
like 2.2GB. To really take full advantage of RAM over 1GB, you need a
64-bit AMD64 or EM64T machine.

When you put DDR memory of a higher frequency into a motherboard that
only supports a lower frequency, the motherboard will clock the RAM down
to the appropriate speed. So you can put DDR400 into a motherboard that
can only use DDR266 or DDR333 and there will be no trouble. However,
mixing RAM of different latencies (CL2.5, CL3, etc.) can cause
instability with some motherboards. Theoretically CAS latency will also
re-adjust to the lowest common denominator among the RAM chips, but it
doesn't always work the way it should. Also, RAM modules that use
different brands of chips (Nanya, Micron, Hynix, Samsung, etc.) can
cause instability as well. What I'm saying is, it should be safe to put
three DDR400 512MB sticks into a KT4VL, but they should all be the same
brand, speed, and CAS latency. BIOS will report less than 1.5GB of
memory due to the aforementioned address space limitations inherent in
32-bit motherboards, but you should still be in or around the 1.3GB
range if that is your goal.

When I wrote the review, a common folk practice was to use DDR400 in
motherboards that couldn't really support it (meaning the frontside bus
was only running at 333mhz, so 400mhz RAM had to clock down to match
it). This was done with the expectation of higher performance, but in
reality it would perform identically to DDR333. Chalk it up to marketing
on the part of RAM manufacturers. If you overclock, you will need
DDR400, but there really is no point in overclocking -- you don't get
performance commensurate with the added expense of high-grade heatsink
compound, a heavy-duty heatsink/fan unit, and higher-frequency RAM
(though these days, as you pointed out, DDR400 is more or less the same
cost as DDR333).

Hope that answers your questions.

-Jem Editor In Chief, The Jem Report

http://www.thejemreport.com/mambo/content/view/88/41/

[oldandinthe way]

I think your reviewer is another source of folklore mixed with fact.

The specs for DIMM memory operate independant of how many chips are used to create the DIMM

The 2gb memory limitiation is well documented. Again it is noted in the Intel motherboard manuals. Two 1gb DIMMS work just fine. Expectation that 4 DIMM slots means you gan go to 4GB just ignorance.

More ignorance - expectation that faster memory than your mobo supports will speed up performance.

Mixed brands - more folklore. Perhaps a result of crappy memory houses from long ago. Today, memory is memory, just a commodity. If it really is what it claims to be - it works. Can you get mislabeled or altered product? - sure but not at reputable dealers. I suppose there is a chance that a crappy motherboard based on an inferior support chipset could fail to properly adjust to mixed memories but it really seems a bit far-fetched.

[Cobra]

You are correct that when larger chunks are handled, dual channel is faster. Where you are incorrect is that smaller chunks are not processed quicker.

That's exactly what I said. Just because the RAM can hammer along at a red-hot pace doesn't mean that the CPU will be demanding it at this rate.

[ROF]

You are correct that when larger chunks are handled, dual channel is faster. Where you are incorrect is that smaller chunks are not processed quicker.

That's exactly what I said. Just because the RAM can hammer along at a red-hot pace doesn't mean that the CPU will be demanding it at this rate.

Yes. But if you increase the efficency of the FSB are you not speeding up the processing capability of CPU? Dual Channeled RAM offers this option. If your motherboard supports it, it only makes sense to take advantage of it.

[TBoneit]

Memory limitations come about because of Chipsets on the Mobo and the OS too. Poss. Mobo design too. Back in the days a of socket 7 we had a mobo that could go to a max of 128Mb

And of course the chipset makes a difference. Some Intel chipset boards under XP Pro with 4 1Gb memory for example as stated in the manual (ASUS) show around 3.3Gb total memory as I recall. Customer wanted all he could get so..... 3.3 is still in his case better than 3.0 Gb memory.

[Cobra]

Yes. But if you increase the efficency of the FSB are you not speeding up the processing capability of CPU? Dual Channeled RAM offers this option. If your motherboard supports it, it only makes sense to take advantage of it.

(hope I'm not misunderstanding what you said)

The FSB is independent of dual-channel memory. You know that dual-channel RAM is brought about by giving each stick a separate memory controller. However, the FSB remains unaltered. Therefore, installing dual-channel RAM has no bearing on the CPU speed itself, but does significantly increase the memory bandwidth available. This makes the system itself run quicker as the CPU can get data faster - less waiting about for the RAM to deliver data for processing.

[ROF]

All these technical terms. What does the FSB do? The Front Side Bus is the interconnect between the CPU, the system memory, and the rest of the system. If dual channel DDR can send and receive data twice as fast and the motherboard socket(ie. where the CPU sits) is capable of supporting dual channel DDR, there is a relative increase in the speed with which data passes through the FSB thus increasing the efficency and capability of the FSB. It does not matter for the size of the data. All data is passed through these parts quicker.

Think of it this way. The FSB inside a single channel system is shuffling data between the RAM, the CPU, and other points in between the same way a horse and carriage ferries passengers between rural communities and townships. The FSB inside a dual channel system is shuffling data between the RAM, the CPU, and other points in between the same way a modern day bus would ferry passengers between rural communities and townships.

When given the chance to remove any bottleneck inside a system, the end user should definitely take advantage of it especially when there is nearly zero cost to do so. The difference between a single 1GB stick for DDR400 and 2x512MB sticks of DDR400 when bought in pairs is negligible or zero difference. In some cases, it's even cheaper.

[oldandinthe way]

Folks

You are ignoring the word "interleave". Dual channel interleave always is faster than single channel, independant of processor loading. Interleaved memory processes consecutive memory locations from two different DIMMS. It thereby avoids the full latency of the memory. With even the slowest FSB this improves performance.

[Cobra]

I know what the FSB does.

When given the chance to remove any bottleneck inside a system, the end user should definitely take advantage of it especially when there is nearly zero cost to do so.

I agree with this completely. Let's ignore how the benefit comes about, and concentrate on the fact that it is there and should be taken advantage of.

By the way, some dual-channel kits are actually cheaper than one module. Not sure if that was just weird pricing at the retailer, or whether two paired sticks with less capacity are simply cheaper to produce than one big one, but you can get more performance for less in some cases. Nice.

[Doramius]

Let's just leave it at this. If you have the ability to run dual channel or 2x512MB RAM for the same or less price than 1x1GB RAM, do it. If but for this reason alone, it will help keep the dust out and off the socket for when you upgrade to 2x1GB sticks just to barely meet the minimum requirements for WinVista. :P

[Nelson37]

Two sticks are often cheaper because the highest-capacity chips (in the single module) demand the highest prices.

Two sticks are better than one in the dual-channel setup. Not a whole hell of a lot, but there is a speed difference. Since it is actually cheaper in most cases, you are being paid to upgrade performance.

Different sticks, whether speed, brand, or whatever difference, can and do cause problems when mixed in systems. Not always, and not always immediately obvious. Avoid mixing sticks if at all possible.

Last two statements are backed by repeated and recent field experience, both benchmark and real-world speed tests run with varying configurations, or repeated observed errors, which did not occur in multiple tests with matching memory sticks.

[kosekjm]

Hi there,

One other thing that I'd recommend, is to check a website like http://www.crucial.com They've been selling memory for a long time (I think even back to those 386 days that kschang mentioned). They have their memory checker that lists a lot of different MB/System manufacturers that you can see what they recommend for your system. No guarantee that they list yours, but its free to look

I've used their site many times to verify compatability for friends and family members before purchasing ram for them and so far I've not had any complaints.

Just a thought.

[TBoneit]

IMHO Dual Channel benefit to the system is anologous to striping two hard drives to improve data transfer. Short explanation is that Dual Channel is striping for memory.