# Sorry I don't understand High Density and Low yet



## Kalim (Nov 24, 2006)

> Why not start with your first post today and become an active part Tech Support Forum forums now!


Jee thanks  I will do now.

Hi everyone

Nice site, I hope it does well.

I needed some information on RAM as I'm buying it for two PC's and I need this in my profession, urgently:

a) with one I've sold its 512MB RAM and opted to buy 2x1GB memory modules
b) the other already has 1.5GB and I'm planning on removing one of the 512MB and replacing it with a 1GB memory module.

Now I know most of the RAM basics, but still, after reading THIS excellent post my a moderator in the sticky, do not understand the ways to know/spot "High Density" and "Low Density" RAM modules 

I'd love some help with these issues. I have this motherboard for one of my PC's: 

http://www.eprom.com/home/Microstar/ms6743g-ls.htm +

http://www.crucial.com/uk/store/listparts.aspx?model=MS-6743G+(865GM2-LS)


> Supports 4 unbuffered DIMM of 2.5 Volt DDR SDRAM
> Supports up to 4GB memory size with non-ECC
> Supports Single or Dual Channel DDR 400*/333/266 MHz and up
> (*In order to use DDR 400, FSB 800 CPU is required)


I knew about DIMM, SIMM, Dual channel, SDRAM, DDR SDRAM, FSB speeds, latency, CL etc... but I didn't know and still am not sure at all what difference and compatibility issues there are with High/Low density modules and single sided and double sided modules??

So in the process of buying memory I bought everything Crucial scan etc, even my motherboard manufacturer said, but when I inserted it, beeeeeeep! Obviously RAM incompatible error. Why? It was exactly the same RAM as before *but* it was double sided instead of single sided.

How can this be explained?

Why can I not put inside some double sided memory sticks?
I have a RAM stick inside but running Memtest86 showed it up with 1500 errors by the Test #5 stage, so I've took it out to chuck away, as it was the source of endless BSoD's.

And I really don't understand the terminology I've heard as in 'ranks'. As far as I understood (at one time and then I was lost) its referring to the correct terminology for single sided and double sided...? Single sided being one rank and double being two rank...?

I may be far out and for that I apologize.

Also I was lost with the mention of 8 bit, 16 bit and 4 bit as I had been reading that the memory bus width is always 4 or 8 bits!?

Further I had purchased a RAM stick from a friend, 1X1GB for £40 PC2700 DIMM 184 pin, and it reads 128x64. Whats all this about?

So many questions, but I hope someone can help a puzzled soul. I'm sure most of you know more than more in this field.

Can someone help please.

Thanks much in advance.


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## Terrister (Apr 18, 2005)

Please read this.
http://www.techsupportforum.com/


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## Kalim (Nov 24, 2006)

Please read my first post which links that exact page right at the beginning and says I've read it and what I don't understand about it follows.


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## BeastlyKings (Nov 13, 2006)

Just think about it, i did not understand before i read but now i do!!!
You see, its like... i don't know how to explain it to you.
But just think and read it,ponder on it.
you will get it.


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## crazijoe (Oct 19, 2004)

I will try and clearify this. 
First, from my experience, every stick of memory that has come from Crucial is Low Density. They want their memory to be 100% compatible. Thus the reasoning behind this.

Next, the motherboard you have posted is a dual channel board. This is probably where your memory errors are comming from. If you do not use a dual channel memory kit you will need to disable this feature in the BIOS.
When you use dual channel, both sticks of memory have to be identical. In otherwords they need to be the same speed, latancy, and size. They basically should come from the same batch. Dual channel kits are tested for compatibility with each other. 

As far as "Ranks", take a single slot for memory on a motherboard. If a manufacturer states the slot is capable of 1GB. This could be taken 2 ways depending on the way the chipset manufacturer runs the memory bus. Either one rank of 1GB or 2 ranks of 512MB. Buying a stick of memory that is double sided does not necissarily mean it is low density. It has to do with the arrangement of the chips on it. You need to look at each individual chips to see how they are arranged. A **x4 chip would be a high density chip.


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## Kalim (Nov 24, 2006)

Thank you very much!









As it turns out, I did already know this and understand this fully, so my confusion was a mistake and only with the rank terminology...and this:

1GB DDR333 *128 x 64*








Now as far as I know, this is 128 MB chips on the module x 8

Whats the 64 stand for then?

BTW, the mobo I've stated above, it supports Single as well as Dual channel. I have ran single sticks in there for two years before now. The Dual channel slots are separate thats all. You probably only read the top section where it states Dual channel 6.4 GB/s (i.e. PC3200 x 2). Here on the same page below it says :


> *Main Memory*
> 
> * Supports 4 unbuffered DIMM of 2.5 Volt DDR SDRAM
> * Supports up to 4GB memory size with non-ECC
> ** Supports Single or Dual Channel DDR 400*/333/266 MHz* and up (*In order to use DDR 400, FSB 800 CPU is required)


My mobo supports 1GB in each slot as you can see.

That brings me to the next question. Does the above mean I have to have a FSB of 800MHz to run DDR400 RAM? Why is that when DDR is double the FSB reading and hence should be DDR1600 if my FSB is 800? I mean I should have DDR400 if I have FSB of 200MHz, right?

Secondly, what is my mobo FSB, do you know from that? (I can't get into the BIOS, no RAM so I can't check)


Still I don't understand, *why would the above motherboard not accept double sided RAM?* It says no where that it shouldn't. I bought it because it never specified which type and I was told both singel sided and double are ok for the mobo. I have low density RAM in at the moment and always have.

Those are my queries I hope you can answer. I do understand RAM pretty well BTW, I've built my own computers at least thrice in the last year (1st time tho) but am confused with this issue I'm experiencing now.


Sorry for the voluminous questions, but teacher to student you see- and so the student will push his thoughtline into area's he doesn't yet know whereas the teacher does. 

Danke


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## Kalim (Nov 24, 2006)

I'm still scratching my head over this


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## crazijoe (Oct 19, 2004)

> Whats the 64 stand for then?


64 is the size of the memory bus. 64 bit



> That brings me to the next question. Does the above mean I have to have a FSB of 800MHz to run DDR400 RAM? Why is that when DDR is double the FSB reading and hence should be DDR1600 if my FSB is 800? I mean I should have DDR400 if I have FSB of 200MHz, right?


Let's look at this a different way. You motherboard clock speed is 200MHz. The front side bus of the CPU is 800MHz (Intel Quad Pumping 200MHz x 4 = 800MHz). The memory front side bus is the same as the MB clock speed (DDR memory passes 2 instructions per clock cycle so it is double the MB clock speed. 200MHz x 2 = 400MHz). FSB of both the memory and the CPU can be changed and be mismatched. You can run slower memory with a faster CPU. The chipset will degrade the speed of the memory bus to match the memory installed. 


> Secondly, what is my mobo FSB, do you know from that? (I can't get into the BIOS, no RAM so I can't check)


For this we need to know the FSB of the CPU.

On the system you are having the problems with, what is the memory configuration you presently have? What modules are you installing and what modules are on the board presently? What slots are the modules in?


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## Kalim (Nov 24, 2006)

Thanks much. Ok I had some Ballistics modules 1.5GB PC2700 installed before but now have reverted back to nothing.

I understand this fully now. I was only basically becoming confused with what another individual has been telling me and trying to reconcile what I know, what she's saying and what your saying made me confused. My initial interpretation was correct I now know. Thanks, your exlanation in the other thread is perfect. Low density is 8 chips and high is more than that with the 64 bit width.

My FSB 64-bit as usual but I've no idea about anymore as I have no RAM to test and power on with. I'm guessing its front side bus 200MHz, Intel Celeron D 2.8 Ghz with 200MHz memory bus speed. Although I'm expecting it would be 400 to 800MHz FSB at least.
The RAM previously installed was 64x8 single rank, single channel, 2 x PC2700 CL2.5, no parity/unbuffered/non ECC DDR333 184 pin SDRAM in slots 1 and 2. One was 512MB and the other was 1GB.

Is it possible to power on and load XP without any RAM inside (just to run Everest)?


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## Kalim (Nov 24, 2006)

Hold on. I think I've quoted the wrong figures for one reading. I've just checked the last RAM I had (out of the bin) and it was double rank with 16 chips to make up 256 MB! That would mean its 16x16 right?

Weird, but when I ran Everest on it a week ago (I have the printout) it read 64-bit bandwidth.

Even more confusing


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## crazijoe (Oct 19, 2004)

All present day PC memory busses are 64bit. Can you boot the computer with a single stick of memory?


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## Kalim (Nov 24, 2006)

Yes that was an error again! 
The old RAM sticks I used successfully on this PC (before the Ballistics were used when overlocking) were 32Mx8, single rank, 8bit a chip if I'm correct. That would mean they are Low Density right?

Well see thats the problem. I only have two double rank 16Mx16 256MB RAM sticks here which do not work in it at all making the beep, and have purchased another single rank 128Mx8 RAM 1GB module 6 days ago which also doesn't work in it. So I can't get it fired up.

So what it looks like clearly is that, it doesn't support High Density nor double rank mem sticks yet this was explained no where by the mobo manuf.!!

Many thanks for all the help and patience so far


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## Kalim (Nov 24, 2006)

Ok. I've just seen this HERE:


> * All low density 1GB modules are made with 16 chips (8 chips on each side) using 64Mx8 device.
> * All high density 1GB modules are made with 16 chips (8 chips on each side) using 128Mx4 device.


Now thats confused me silly! I thought a memory module 128M and 16 chips is 2GB not 1GB?!?

Just when I thought I had it figured.


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## Kalim (Nov 24, 2006)

I'm going to explain what I know and then please correct me where I'm wrong.

A 1GB memory module, with 16 chips, 8 on each side being 128Mx4, is worked out like this:

128M x 8 chip on one side = 1024 MB i.e. 1 GB memory total
4 bit x 16 chips in total = 64 bit memory bus

I'm expecting massive flaws, and its weird as well as pathetic why I'm confused...but I am









Sorry to be a pain.


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## crazijoe (Oct 19, 2004)

We should actually not use the term "High Density" or "Low Density" as most of modern day computers can use either or. It is how the modules are configured and what chips are used. Most modules today are either single rank or double rank. You are correct on your assumption on the 4 bit x 16 chips in total = 64 bit memory bus. This would be a single rank module. If the motherboard will accept a 1GB double rank module, you would need to make sure that each rank, on the stick, was only 512MB using x8 chips. If the module was a single rank, with x4 chips, then only 512MB would show or be not supported at all. 
Now let's take a look at a 512MB single rank module. You motherboard supports 1GB double rank in each slot. This would show and should work flawlessly because each rank on the motherboard supports 512MB and the stick is 512MB single rank. 

If you can get a hold of a known good stick of memory and try it. Just enough to get into the BIOS to manually set it for single channel mode.


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## Kalim (Nov 24, 2006)

I've reread your post and have finally worked it out (ignoring the above posts). I have a few questions though.

*So its the total RANK that makes a RAM stick either Low or High density!

Therefore, 1GB - 16 chips, double sided is 8 bit each and usually one rank per side, in total TWO RANK (8x8=64 twice) and perfect low density.
But the same in 4 bit is double sided, ONE RANK thus its High density (4x16=64 both once)*









Assess me please when you get time on this post and then I cans tore this info deep down in the grey and try to reevaluate everything again for you 

I was making it much much more complex than it is. Await your reply later tonight after getting home from work.


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## Kalim (Nov 24, 2006)

crazijoe said:


> We should actually not use the term "High Density" or "Low Density" as most of modern day computers can use either or. It is how the modules are configured and what chips are used. Most modules today are either single rank or double rank. You are correct on your assumption on the 4 bit x 16 chips in total = 64 bit memory bus. This would be a single rank module. If the motherboard will accept a 1GB double rank module, you would need to make sure that each rank, on the stick, was only 512MB using x8 chips. If the module was a single rank, with x4 chips, then only 512MB would show or be not supported at all.


No, it just makes a massive beeeep when installed and rebooting. Nothing else shows up.


> Now let's take a look at a 512MB single rank module. You motherboard supports 1GB double rank in each slot. This would show and should work flawlessly because each rank on the motherboard supports 512MB and the stick is 512MB single rank.


 Thats if I can get a single rank 512 MB stick or double rank 1GB stick. I don't have one though as the ones I bought are not being supported.

In summary:

*My mobo supports single & dual channel, 1GB per slot, 4GB in total, 4 slots.

*Whats ran perfectly on the system is a 32Mx8-bit PC2700 DDR333 256MB stick: 8 chips, single sided and single rank.

*Whats not running is 256MB 16Mx(I don't know how to tell) PC2100 DDR266 stick: 16 chips, double sided and I don't know the rank.

I can tell what it is even though I have three of these handy, but don't know how to work it out (it doesn't say on the chips themselves).


> If you can get a hold of a known good stick of memory and try it. Just enough to get into the BIOS to manually set it for single channel mode.


I'll have to buy another one. Wait a minute. The one I have of old is corrupt and won't boot up any OS but it still gets passed the POST. Thus if I use that it should work fully for the BIOS!

So in essence my question is:
How do I work out or know if its 8 bit or 4 bit then to know if its one rank or two and high density or low, if it doesn't states so anywhere, is double sided and 16 chips making 1GB RAM? Is there no way to tell without actually running it?

Also are 2 bit or 6 bit chips possible?

Your post has reiterated my understanding now and that my last post is correct. So I can proceed further now to step 2.

Thank you much :grin:


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## Kalim (Nov 24, 2006)

After this - I've found put away in my cupboards, the sticker reads:
*1GB PC2100 128M x 64-bit RAM module, 16 chips, double sided.*

Isn't that virtually impossible?! That would mean its 16 RANK right?....

I think it should be printed *128Mx4-bit* instead and that would give it a 'ONE RANK' reading for the whole module.

Now thats High Density right?

Its made by Samsung which I know to be probably one of the best manufacturers of RAM out there. I'm guna give a whirl in about 10 minutes to see if it works :|


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## crazijoe (Oct 19, 2004)

> 1GB PC2100 128M x 64-bit RAM


You must be reading the lable on it. the 64-bit means 64 bit memory bus. Look at each chip.


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## Kalim (Nov 24, 2006)

The chip doesn't read anything but some codes. The label on it reads 

*1BG DDR PC-2100
128x64 HIGH DENSITY DDR
Warranty Void Id removed*


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## Kalim (Nov 24, 2006)

HAHA it worked!!!









I put in the 128Mx4-bit memory modules in there, two 1GB PC2100 DDR ones, each with 16 chips and my computer picked them up and runs wisko!!

It picks up 2048 in many utilities such as Motherboard Monitor, SiS Sandra Lite, CPU-Z, PC Wizard, Everest, Belarc and in System Properties too.

No need to buy anything more!

Thank you so much for the help *crazijoe*...indebted

Two questions for future: 
1. How can I recognize High from Low Density RAM (if there's no stickers on it)?
2. How can I know without trying if a motherboard supports High Density?

By the looks of it, it seems one has to try it or you can never know...

I have some spare RAM if your interested in buying?....lol


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## Kalim (Nov 24, 2006)

Actually another question... why do all these utilities show my memory bus speed is at 100MHz???? When its supposed to be 133MHz and DDR266 when running PC-2100?


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## crazijoe (Oct 19, 2004)

> 1. How can I recognize High from Low Density RAM (if there's no stickers on it)?


The only way is with any identification on the chips or if the vendor is willing to release that info.



> 2. How can I know without trying if a motherboard supports High Density?


The technical data for the motherboard. Seeing how many ranks are in each slot and what each rank will handle. I have seen some motherboards that will have 3 slots. The first slot will accept a double rank module and the 2nd and 3rd slot will only accept a single rank module. 
Most VIA chipset boards will accept high density. 95% of the Intel chipset boards will not. I usually always buy low density memory to prevent a compatibility issues. It's usually worth the extra expense.


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## crazijoe (Oct 19, 2004)

Kalim said:


> Actually another question... why do all these utilities show my memory bus speed is at 100MHz???? When its supposed to be 133MHz and DDR266 when running PC-2100?


The memory bus speed is dependent on the FSB speed of the processor. If you have a processor with a FSB speed of 400MHz. Then the MB clock speed is 100MHz. 
If you had a processor with a FSB speed of 533MHz, then the MB clock speed would be 133MHz. 
Then memory speed has been downgraded because it is not neccissary to run at it's advertised speed.


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## Kalim (Nov 24, 2006)

Wow. Thank you. That about resolves everything of RAM issues I had. I only have a MS Photo Editor issue left which no one is replying to in the Windows XP forum.

Thanks much. You've been excellent against my ignorance


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