[proux]

After a search in these forums there seems to be some confusion about this. Theoreticaly only PC150 CL3 should run like a PC100 CL2 (3->2 150->100). Someone mentioned may it would run 322 and not 222 (CL2). Any insight?

It has been stated that there is not much difference between CL3 and CL2 but my other Ram is CL2...

This is because you can find some 512mb PC133 for as low as $40, but PC100 CL2 is about $70. Please help, my Cube needs more Ram!

[BurpetheadX]

some PC-1XX RAM are backwards compatible. I have a few chips that are PC-133 that have a tag on them saying they will work as PC-100's. I think its just the brand you buy. I dont know much about CL2/3, but I do know that CL2 has a faster bus or something, thus making the memory a tad faster.

[douthat]

CL stands for "CAS latency," which is the number of clock cycles it takes before data starts to flow once a command is received. Low CAS latency is faster than high CAS latency. However, faster memory will NOT necessarily make your system faster. Your computer will only run as fast as the "slowest link" in your system, so you can't speed up your computer by adding memory that is faster than your current memory.

I would stick with CL2. If you have CL2 and you buy CL3, it will slow down all the memory in your system.

[douthat]

Oh yeah, and memory speed is set by the controller, not the sticks. The difference between PC133 and PC100 memory is that PC133 has been "certified" to run at up to 133MHz... so you can buy the 133 memory and stick it in your PC100 machine and it will run just fine

[schalliol]

The last post about PC133 RAM running fine in PC100 machines is not correct. Some does, but there can be problems.

In fact, I bought some Kingston RAM to stuff in a G4/450 (PCI Graphics), but of the 4 modules I tried, they always gave 1/2 the RAM indicated and in fact caused Mac OS X system level problems. I took that same RAM and stuffed it in my G4/733 (Digital Audio) and it works incredibly well).

Where did you find $40 512MB RAM? I know that some of mine is CL3, so I guess I should just buy a module or two of that.

[schalliol]

Also, that RAM even indicated specific PC Chipsets it wouldn't work on for PC100....So, make sure you can return PC133 RAM if you buy it for a PC100 machine.

[douthat]

Originally posted by schalliol:
The last post about PC133 RAM running fine in PC100 machines is not correct. Some does, but there can be problems.

In fact, I bought some Kingston RAM to stuff in a G4/450 (PCI Graphics), but of the 4 modules I tried, they always gave 1/2 the RAM indicated and in fact caused Mac OS X system level problems. I took that same RAM and stuffed it in my G4/733 (Digital Audio) and it works incredibly well).

Where did you find $40 512MB RAM? I know that some of mine is CL3, so I guess I should just buy a module or two of that.

I really don't think that's true. There is a possibility that the 450 machine's bios may have had a bug in it. PC133 RAM was designed to be backwards compatible...

http://www.techtv.com/screensavers/a...346466,00.html

[sideus]

http://forums.macnn.com/showthread.p...hreadid=137945

[proux]

I think they are backward compatible.
It looks like 512mb modeles around $43 on dealram.com.

Anyway my original question is not if the PC133 module will work with a PC100, but if the system will recognise the speed as CAS2.

[schalliol]

My point was that they may be backwards compatible and don't wish to have something written on the Internet that's incorrect Haha, there's lots on the Internet that's false, but people searching here shouldn't be buying the wrong stuff.

Thanks for the RAM heads up!

[Avon]

Originally posted by schalliol:
The last post about PC133 RAM running fine in PC100 machines is not correct. Some does, but there can be problems.

In fact, I bought some Kingston RAM to stuff in a G4/450 (PCI Graphics), but of the 4 modules I tried, they always gave 1/2 the RAM indicated and in fact caused Mac OS X system level problems. I took that same RAM and stuffed it in my G4/733 (Digital Audio) and it works incredibly well).

Where did you find $40 512MB RAM? I know that some of mine is CL3, so I guess I should just buy a module or two of that.

This is not becasue of the speed of the ram. I have never bought ram that did not run at under the advertized speed.

Your problem was caused because the computer cannot address the ram chips on the DIMM. They where probably 32 meg chips. Older machines can only use 16 meg chips. I had the same problem in a BW G3. I returned the 32X8 single sided DIMM and I got a 16X16 double sided DIMM.

[Eug]

I don't know anything about the cube but:

RAM will be backwards compatible. PC133 CL3 should run fine at 100, and at CL2. Remember than PC133 CL3 is actually higher spec'd than PC100 CL2.

BUT:

On the PC side, 512 MB RAM sticks are problematic. Certain chipsets are NOT compatible with them. Later chipsets would work fine with the same sticks however.

This is in contrast to say 64 MB RAM sticks which would work in essentially any machine.

[proux]

"RAM will be backwards compatible. PC133 CL3 should run fine at 100"

So you sure about that one?





You do you make these damn quote, the button doesn't do anything...

[schalliol]

So the issues are density of RAM (probably most important in 512's than anything else) & speed.

I know you won't like this, but rather than spending $30 of your time trying to figure this out, just go to crucial.com and put your machine in and buy the CL2 RAM they list. They have free FedEx shipping and I just bought a 512MB module and got a $8 coupon advertised right there (said it was specific to me). You may want to try to clear your cookies.

I can check it out when I get it, I imagine that I should be able to tell the density when I get it (don't know how, but I'll figure it out, counting the number of chips?). That will at least let us know if the density works in the Digital Audio PC133 machines....I've done a search and I have seen NOONE that has identified 4X64 units working in even these machines....as a result, you MUST be careful when you order yours that they are the appropriate units. I know it's not exactly what you're asking, but if you don't heed this advice, you may get RAM working as 256, instead of 512.

[schalliol]

It does depend, remember what I said about the Kingston RAM, you must be sure about the density of RAM. If you REALLY want the cheapest price, call Crucial, ask them what their units are that work in your unit, then search this out on the net.

[D'Espice]

schalliol: You know you can EDIT your posts, don't you?

@all:
You're missing the point here. The question is not whether PC133 RAM will run in a PC100 computer (which IMHO it always does, I'm with douthat on this one, although there might be a problem which I will explain later) but whether PC133 CL3 will run at 100 MHz with CAS-Latency 2
And I can give you a certain answer to this: Depends on the stick. There is no general rule whether PC133/333 will run at 100/222 or not, some sticks do some don't. I have two 256MB PC133 CL3 sticks, both Infineon. One is running just fine at 100/222 the other causes crashes at that speed, I have to run it with 100/322.

About PC133 <- PC100 compatibility: In general, douthat is absolutely right. PC133 specifies that the memory stick has been tested and is certified to run up to 133 MHz with the specified CAS Latency, RAS-CAS delay and RAS latency (333 or 322 or 222 or whatever). Each single memory stick has a SPD-EEPROM into which - among other things - these specs are written. The mainboard's BIOS can now read the SPD-EEPROM and automatically determine at which speed the memory stick will run with which latency. Intel and AMD mainboards almost always offer the possibility to change these values manually by ignoring the SPD-EEPROM settings. Therefore with a PC, you can manually set the latencies. Apple computers don't do that, they always read the SPD-EEPROM and determine the settings by comparing the different specs for different memory modules and chosing the slowest setting allowed.
Now if the SPD-EEPROM does _not_ have an entry for 100 MHz then there might (!!!!!) be problems running it in a Mac computer. Let's say you have two memory sticks, one that has been tested and specified for PC100/222 and one without a PC100 entry in its SPD-EEPROM. The slowest setting found by the mainboard's BIOS is the PC100/222 setting, therefore both modules are running at 100 MHz with 222 latencies. Now if the stick without the SPD-EEPROM entry is not certified for 100/222, it might cause major headaches and crashes in case i doesn't run at that speed. However it doesn't have to cause trouble if it's compatible but the manufacturer simply forgot to write the PC100 specification into the SPD-EEPROM.
The next problem will be if you only have sticks without a valid PC100 SPD-EEPROM entry. I have never tested it but I guess that the mainboard won't recognize a proper setting and run it hat 100/333. I'm not sure about this one though. But as long as you have one memory stick with a 100/333 entry in its SPD-EEPROM you can use every single PC100, PC133 and PC150 stick out there, regardless of its SPD-EEPROM entries.

In general, PC133 is always compatible to PC100 and PC66.

[schalliol]

I do know how to edit my posts, it was just faster that way, I didn't know that it caused any problems in any way (and maintain that it doesn't).

So, with your big post, I don't know how that helps this person select RAM, it seems that the problem may around the density of RAM on the chip, relating to my post where I tested 4 Kingston modules in a G4/450 (PCI Graphics) and found that they gave half and caused problems as well. In that post I also indicated that the PC133 RAM worked fine in my G4/733.

Since you seem know all the specifics on the RAM, show us some modules that will work.

[D'Espice]

The chip density is a totally different problem that is NOT only Mac-related and does have NOTHING to do with whether it's PC133 or PC100. High density chips don't run in older Macs, here's why:

Say the BIOS/chipset can support up to 128 MBit x 16 that would be a double-sided 256 MByte stick. However 256 MByte can be achieved in other ways too, like for example 256 MBit x 8 or 512 MBit x 4. The last two are "high density" ram that will NOT run in a Sawtooth and probably also DA because the BIOS/Chipset will only recognize either 128 MBit x 8 (128 MByte) or nothing at all.

[schalliol]

D'Espice, thanks for the info. I think we all now understand the deal with PC133 vs. PC100 and CL2 vs. CL3. A question though, knowing that we need some good entries in the SPD-EEPROM, I don't see any way of telling if this is set before purchase. That said, since we're talking about how to buy the right RAM, how do you determine this before purchase? I have yet to see RAM advertised that it has all the settings in the SPD-EEPROM (though I haven't looked for this much). The best way I can tell is by seeing who has supported this for the particular machines (i.e. Crucial.com). If they say that it works in it, it ought to work to the specs they indicate.

I understand that the density is another problem, but don't you think it's integral to chip purchasing decisions?

Someone may end up getting even a 512MB PC150 CL2 with all the correct SPD-EEPROM settings, but if it's the wrong density, it still won't work as it should. Correct?

After all this deliberation, it seems that the appropriate response (other than the following case) is to buy from someone who indicates that the RAM will work as spec'd in your machine (or motherboard) because they're not going to tell you about the SPD-EEPROM settings or the density may not be known and cause undesired results.

If you go by specs alone (assuming you don't have SPD-EEPROM entry information), this is the only thing I can see that you can be sure will work in a PC100 Mac at CL2 (correct me if I'm wrong):

PC100 CL2 low density RAM (128Mbit x 16)

[D'Espice]

Well, I think I might have just painted a horrific picture there It's not that bad though. You have to look out for certain things:

- Don't buy high density RAM, it won't work. You can check the stick's internal organization by looking at the sticker, there's almost always some information on it

- Don't buy RAM that is officially NOT specified for PC100, e.g. the box says "not PC100 compatible" or something like that. These sticks most probably don't have SPD-EEPROM entries therefore may cause trouble as described above.
RAM that is not officially not specified for PC100 (what a sentence...) will most probably work just fine, as long as it's not high density RAM.

- If you want to be 100% sure, get RAM that is officially specified to run in your machine, e.g. Crucial or OWC or whathever.

- If you want to buy at CompUSA or some other store, you can ask the salesperson whether he/she can pop in the stick into a computer and whether you can check something about the SPD-EEPROM entries. Get this program, it's a windows program that reads the SPD-EEPROM so you can take a look at it before you actually have to buy the stick.

[schalliol]

Additionally, don't put Kingston PC133 units (I assume all, I tried 128 & 256) in PC100 - I believe that they have the density problem. I know we covered it, but since 4 of these units didn't work when tested, don't bother.

[proux]

Thanks for all the replies. I guess the answer to my original question is "maybe"... I will buy a tick next week and let you know.

[reverb]

I know you won't like this, but rather than spending $30 of your time trying to figure this out, just go to crucial.com and put your machine in and buy the CL2 RAM they list. They have free FedEx shipping and I just bought a 512MB module and got a $8 coupon advertised right there (said it was specific to me). You may want to try to clear your cookies.

Crucial does not sell a 512MB PC133 CL2 module for use in Macs, and they do not warrant any 512MB PC133 CL2 modules found elsewhere on their site to be stable in Macs.

The 512MB PC133 module listed for Macs with the $8 coupon, part number CT242180, is clearly indicated as CL3.

My QS DP 1GHz shipped with a Micron 512MB CL3 module from the factory. I matched it up with two more Micron 512MB CL3 modules from Crucial after speaking to them and Apple on a number of occassions.

[schalliol]

I beg to differ:

I went through the utility to find RAM and got to "Apple Power Mac G4 (466, 533, 667, and 733MHz)" and saw this:

These 168-pin DIMM modules are compatible with your Apple Power Mac G4 (466, 533, 667, and 733MHz)
512MB CT223768: "? SDRAM, PC133 ? CL=2 ? Non-parity ?" The price was and still is $82.99 and there's an $8 coupon.

Just below it there is:
512MB CT223767: "? SDRAM, PC133 ? CL=2 ? Non-parity ?" Has the same price and the same couon.

In my email order summary of the ...768 "Part Number: CT64M64S4D7E" was displayed if you want to talk to them.

[reverb]

Okay, let me re-phrase that...

Crucial sells no SDRAM 512MB PC133 CL2 modules specifically for Power Mac computers with G4 processors running at 800MHz or higher. Nor do they warrant any such modules that may be generally available from them to be stable in said Macs.

[schalliol]

Then why do they locate those modules under 466 - 733 machines? They specifically state that they work in those machines on the website.

[schalliol]

In relation to above posts, my 512MB Micron CL2 PC133 unit arrived today and seems to work great (as indicated on their website that it would).

Mac OS 9 had the ability to monitor the CL of chips in Apple System Profiler. Anyone know of such a utility in OS X or one that checks the memory throughput, etc? I searched on versiontracker and only found items reporting the amount of used RAM and allocations.

[reverb]

Mac OS 9 had the ability to monitor the CL of chips in Apple System Profiler.

Note that this is notoriously unreliable. Though not due to the OS but the controller chip on the RAM module. ASP is not monitoring anything, rather it is reporting information stored in the module which may be set by unscrupulous RAM "assemblers" to report CL2 when the module was actually CL3. This was a oft discussed issue last summer, perhaps at XLR8 though I don't recall exactly where all our banter took place.

However, I would certainly believe that the modules you received from Crucial were CL2, and be cautious of generic suppliers.

[reverb]

Then why do they locate those modules under 466 - 733 machines? They specifically state that they work in those machines on the website.

I don't understand your question.

They, being Crucial, offer CL2 under those machines and specifically warrant them to function reliably in those machines. Correct.

They do not offer 512MB PC133 CL2 modules for the more recent G4 machines that I noted because they will not warrant these modules to function reliably in them. In other words, for the most stable machine Crucial does not recommend the installation of 512MB PC133 CL2 modules in machines for which they do not specify them.

[schalliol]

reverb, I now understand your point. I see, it's just an issue with newer machines than the digital audio units. Sorry for the confusion.

[Camelot]

Folks,

The reality is it doesn't matter!

If you're buying the cheapest memory you can find, it's only going to last a couple of weeks, anyway!

Then you'll waste all those precious picoseconds you saved by using PC133/222 over PC100/322 by calling up the company you bought from and requesting an RMA.

For all intents and purposes, no one is going to notice the difference between 322 and 222 as long as it's supported by your system. Check the Apple spec database and go with that.