PC memory question

Billson · Jul 31, 2006

I've been shopping around for a 256MB 168-pin SDRAM because the one in my 6 yr old PC conked out. Will I encounter compatibility problems if I buy without actually testing it in my system.

I've come across some terms like CAS latency, unbuffered, ECC, etc. but don't have an idea what they mean or what benefits they provide.

Could somebody give me some tips on how to go about looking for what I need?

TigerhawkT3 · Jul 31, 2006

As long as you have the correct speed and type, you should be fine. For example, my mobo takes 400MHz DDR, and I used to have a mobo that took 400MHz RDRAM (not as popular as I expected, by the way). If you're worried about whether it will work, buy it from somewhere you can return it to, like Fry's. CompUSA has a 15% restocking fee on returns. :rant:

Needless to say, I don't buy from them anymore.

Your PC is 6 years old? Wow. You might actually have a tough time finding new parts for it. Have you thought about replacing the entire computer? Sometimes it's not worth it to spend money on a machine on its last legs anyway.

By the way: SDRAM stands for Synchronous Dynamic Random Access Memory, so saying SDRAM memory is like saying Synchronous Dynamic Random Access Memory memory. That last "memory" is redundant, like in "ATM machine," "LCD display," etc.

jtr1962 · Jul 31, 2006

The only problem you might have is if your system takes 256 MB maximum per slot. If so, then you have to use double-sided 256 MB DIMMs instead of single-sided.

allthatwhichis · Jul 31, 2006

Hmmm, this is my area of expertise, but I am not sure where to start.

TigerhawkT3 said:
Have you thought about replacing the entire computer? Sometimes it's not worth it to spend money on a machine on its last legs anyway.

That's is a very valid question. You may even want to look on eBay for your whole machine, that way you have other extra parts and you know the RAM is compatable.

CAS = RAM timings. You should try to get these the same.
Buffered/ECC (error correction) I think are the same, and are usually for servers.
Your probably looking for pc100 or 133, meaning the RAM's speed, like processor speed is 100 or 133MHz. Since it is 168 pin, it will NOT be DDR (double data rate).

Again, it may be easier to get a new PC. That's what I prefer to do... :grin2:

watt4 · Jul 31, 2006

ebay is a good place to find memory for older machines.

Billson · Jul 31, 2006

TigerhawkT3s said:
Your PC is 6 years old? Wow. You might actually have a tough time finding new parts for it. Have you thought about replacing the entire computer? Sometimes it's not worth it to spend money on a machine on its last leg anyway

My PC is mostly used for surfing and word processing so it's plenty fast for these purposes. I've thought about buying a new PC but seeing that a 256MB SDRAM costs only around $25-30, I figure it's worth it. I actually assembled this PC from parts scavenged from 3 different PC's.

I just looked up the specs and it's a Celeron 433 socket 370. The FSB is 66.6MHz so you can imagine how old it is.

jtr1962 said:
The only problem you might have is if your system takes 256 MB maximum per slot. If so, then you have to use double-sided 256 MB DIMMs instead of single-sided.

My mobo supports up to 384MB and has 3 slots so does that mean it can only take 128 MB per slot?

allthatwhichis said:
CAS = RAM timings. You should try to get these the same.
Buffered/ECC (error correction) I think are the same, and are usually for servers.
Your probably looking for pc100 or 133, meaning the RAM's speed, like processor speed is 100 or 133MHz. Since it is 168 pin, it will NOT be DDR (double data rate).

You're correct. It's not DDR. Does it matter if I use PC100 or PC133 memory? What will happen if I mix and match different speeds. Lastly, since I already have an existing stick, what happens if the CAS latency is different between the memory sticks.

Thanks all for the info.

Mad1 · Jul 31, 2006

Firstly it doesn't matter if you use PC133 or PC100 but PC133 is faster (the number relates to the speed in MHz) if the board doesn't support PC133 then it will slow the ram to PC100.

You may be able to put a stick of 256 in one slot and a stick of 128 in the other. Your motherboard is probably so old that the max amount of ram around at the time was 128. :laughing:

The more ram you have the faster you pc will be.

If you mix and match different speeds the ram will default to the slowest.
i.e. if you have a 128mb PC100 and a 128mb PC133 then they will both run at PC100

There is a saying "your pc is only as fast as its slowest component"

Crucial is a good place to get ram from. They guarantee it to be compatible.
http://www.crucial.com/

Hope that helps.

chesterqw · Jul 31, 2006

Mad1 said:
The more ram you have the faster you pc will be.

meep! not correct but not really wrong either.

how fast your comp is depends on many things...

Mad1 · Jul 31, 2006

:touche:

Ok I'll elaborate on what I meant

The more ram you have the more applications you can run at once without slowing down the computer.

The windows kernel isn't the greatest at sharing resources.

bfg9000 · Jul 31, 2006

The main incompatibility problem is depending on what chipset is on the board, it may only accept "low density" modules ("high density" modules may actually work but only part of the stick, eg 32MB of the 256MB, can be seen). Even if a 256MB stick is double-sided, that is no guarantee that is actually mapped as low density. The other incompatibility problem is the SPD on PC100 or PC133 may not actually carry timings for PC66; a proprietary BIOS like a HP or DELL may refuse to boot with such a module (to gently encourage you to buy upgrades from them), while enthusiast boards with overclocking options usually ignore the SPD anyway and let you set the timings manually. In such a board mixing sticks with different ratings is OK.

The 384MB limit usually only means 128MB modules were the largest available when the manual was printed. Intel P6 chipsets all the way back to 1997 support a maximum of 256MB low-density per slot with some chipsets (i810, i815) having a global 512MB limit.

256MB is OK for running XP and 512MB+ is ideal.

cerbie · Jul 31, 2006

If you don't mind paying a little premium, Crucial will sell you RAM they garuntee to work.

InfidelCastro · Aug 1, 2006

Billson, I have a high quality, double sided PC-133 Cas 2 (cas latency 2) 256MB Crucial SDRAM chip I will send you for free. It should work fine at PC-66 speed which is less than half of the spec'd speed of the chip. PC133 will run over 150Mhz @ cas 3. I also have a cheaper double sided memory chip that is rated at PC133 256MB Cas 3, but I know it won't work on your system. At least I highly doubt it. It did not work in mine which is about 4 years old and was originally a 733Mhz. I found a 1.1Ghz chip on Ebay for $10 a couple of months ago and now I have 512MB ram instead of 256 thanks to forum member Uriah.

I'm not totally sure the Crucial chip will work, but I'm guessing it will. I think it may work if you try it alone. Please first try it alone and see what you get. Then you may be able to add more later. Probably not more than an extra 128MB stick though. Even with a bios update (if one exists) 384MB will probably always be max for that system.

CPF member Uriah helped me out with my memory problem on my old PIII system and I would like to help out another CPF with theirs. Please PM with your mailing address and I'll get the Crucial chip mailed out to you as soon as possible.

I'll mail you both chips, since neither does good for me.

Billson · Aug 1, 2006

InfidelCastro said:
Billson, I have a high quality, double sided PC-133 Cas 2 (cas latency 2) 256MB Crucial SDRAM chip I will send you for free. It should work fine at PC-66 speed which is less than half of the spec'd speed of the chip. PC133 will run over 150Mhz @ cas 3. I also have a cheaper double sided memory chip that is rated at PC133 256MB Cas 3, but I know it won't work on your system. At least I highly doubt it. It did not work in mine which is about 4 years old and was originally a 733Mhz. I found a 1.1Ghz chip on Ebay for $10 a couple of months ago and now I have 512MB ram instead of 256 thanks to forum member Uriah.

I'm not totally sure the Crucial chip will work, but I'm guessing it will. I think it may work if you try it alone. Please first try it alone and see what you get. Then you may be able to add more later. Probably not more than an extra 128MB stick though. Even with a bios update (if one exists) 384MB will probably always be max for that system.

CPF member Uriah helped me out with my memory problem on my old PIII system and I would like to help out another CPF with theirs. Please PM with your mailing address and I'll get the Crucial chip mailed out to you as soon as possible.

I'll mail you both chips, since neither does good for me.

Thanks is all I could think of to say.:twothumbs

Btw, pm sent.

Donovan · Aug 1, 2006

A good place to check to see what kind, type and size of memory your system supports is to use the Crucial Memory Advisor Tool at: www.crucial.com
They have a very good, up-to-date database.
You don't have to purchase there to use the tool but they do have decent prices. I usually start there and then check newegg.com or zipzoomfly.com to see if they have a better price...

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