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Which is better for PC100 2-2-2? PC100 CAS2 or PC133 CAS3?

N

Noriaki

Lifer
128MB Mushkin PC100 CAS2: $149

128MB Mushkin Budget PC133: $109

I just want to run at PC100 2-2-2, maybe 110Mhz max, I will NOT be running this RAM at PC133. My motherboard does not support it, and my next motherboard will not likely be an SDRAM board.

I don't want to spend more than I must to get PC100 at 2-2-2, but actually getting it running at those ratings is most important.

So do you think the budget PC133 will run at PC100 2-2-2 or should I get the more expense High Quality PC100?
 
Hey, just get the 2-2-2's then. Slightly lowere latency and because you won't be needin' to go higher than 110... unless later your going to get a 133 mobo, then don't they make 133mhz 2-2-2's as well?
 
Hrmm I think I sort of garbled that question lol...

What I meant to ask is will the cheaper PC133 CAS3 run at 100Mhz 2-2-2, or should I get the more expensive PC100 2-2-2 ?
 
i don't think u find any difference exept u use video editing or photo editing where the extra 33Mhz make the difference, i have 2 sticks 1 pc100 cas2 (although its generic) and the other one is pc133 cas3, using one of them each time made no differce either on 3dmark or quake 3 (differences of 1-2 fps up or down r within error limits) i would get for 133mhz so i could use it for overclocking far more than 133Mhz.
right now both memory sticks run at 140Mhz (isn't taht impressive for the pc100 stick?)
 
People, listen to his question, I would answer, but I honestly don't know...the memory experts around here are Russ, and CRV, and a few others...but I can't remember their names. I do know that Mushkin sells stuff that will do 133mHz at 2-2-2, cause I have 2 sticks. Just putting in CAS2 RAM will not make it run at CAS2...ever heard of the BIOS?
 
Hrmm perhaps i'm not making myself clear enough.
It might be easier if I explain what I'm trying to do instead of asking an open ended question, so here it is:

I have 128MB of RAM right now. It happens to be rated as PC100 CAS2.
In my BIOS it is set to latencies of 2-2-2, and it's running at 100Mhz.

I just want another 128MB of RAM that will run stabily at 100-110Mhz at 2-2-2 ratings. I don't actually care what the markings on the RAM are. I have it set in my BIOS to the timings I want, I just want to find another stick of RAM that will be stable at that setting.

I could buy Rev2 PC133 2-2-2 and it would run fine at PC100 2-2-2, but I think that's more expensvie than I need. I don't mind spending the money if I need that, but I think I could find RAM that cost less and would do the same thing for me.
If I can buy PC133 Budget for $110, and then get it to run stable at PC100 2-2-2 (by forcing the settings in the BIOS) I would be happy.

My question is, will this work. I don't know if RAM rated at PC133 CAS3 will work ok if I tune it down to 100Mhz but force it to use 2 cycle timing.
 
I understand the question perfectly. Open up that fat wallet and spring for some more PC-100 2-2-2's for $149...
 
I'm kind of under the impression that if you take a stick of pc133 cas3 and run it at pc100 you can set it to cas2 just fine. I though the lower frequency would allow for faster timings since the chips are rated faster. But I am not that smart. My siemens pc100 cas3 runs ok at cas2. It will also run 138mhz cas3. Then again I'm poor and cut corners when possible. WTF do I know though.
 
<<I understand the question perfectly. Open up that fat wallet and spring for some more PC-100 2-2-2's for $149... >>
Apperently you DON'T Rambus guy.

PC-100 2,2,2 ~ 125Mhz
So PC-133 will run at 100Mhz 2,2,2.

Be smart Noriaki, and save yourself some money.
 
I'm with office boy. If latency didn't dipend on speed then why is it some people can run up to say 145 at cas2 and up to 155 at cas3 with the same stick of ram.
 
AMB..I know it would be faster to run at 133Mhz.

But as I said before I can't. I have an Asus K7M, this is based on the AMD751 northbrige, PC100 RAM only.

I have an Athlon550 and I'm going to get a big heatsink and a GFD, and crank it up a bit (it's a 650 core, i'm shooting for 700/750), I have no desire at all to change my motherboard, therefore the fastest RAM I can use is PC100. So I am trying to make sure my PC100 RAM is set up to be as fast as PC100 can be, because I can't use the faster PC133, I'd like to, but I can't.
 
Why does this whole thread seem so confused?
Every ram will work at lower speeds. I can put PC-150 (cl2) in an LX board and run it at 66Mhz, and it will be fine.
So would any other speed. If your MB only supports 100Mhz, YOU CAN get faster ram... The only thing is that your motherboard can't use the speed!
 
Officeboy, you just don't need to talk to me like that no matter what memory I prefer. I am very curious how you can calculate that no matter what, any PC-133 can run @ PC-100 2-2-2....
 
OK,

I read this thread, and I am in a similar boat. We have some servers running 100MHz bus speeds, and the current memory is 100Mhz CAS2 nonregistered, unbuffered ECC memory.

I want to purchase mix/match new sticks with the current memory.

Since I am going to be buying 256MB ECC SDRAM, and I have decided to go with Crucial, I am left with two interesting options.

for the 100MHz they have CAS2
CT32M72S4D8E for $264.59 per stick -> update dropped to $243.89

for the 133MHz they have CAS3
CT32M72S4D75 at $283.49 per stick -> update dropped to $264.59

they only have CAS2 133MHz memory in registered, so it is not compatable. (7e at the end).

The sales guy said that officially the 100MHz CAS2 memory was what I should buy, but I could mix 133MHz CAS3 memory in, and it would run fine at 100MHz mixed with the old memory. I am planning on purchasing the 133 MHz memory in the case that we need to migrate these to a new system. Does anyone see any problems with this, or have suggestions as to an alternate action? I'm buying 1.5GB of memory to split between two servers, and it looks like it's worth buying the 133MHz memory to ensure a little bit of future-proofing. (e.g. move the memory to other servers as necessary)

Thanks,

 
boy this is turning out to be complicated...
I know full well that PC133 RAM will work just fine in my motherboard or PC150...I just want RAM that will run stable at 100Mhz with 2-2-2 cycle timing...I'm trying to save my self a few dollars by going with PC133 CAS3 rather than the more expensive PC100 CAS2.
I do not care AT ALL, what numbers the RAM says on it.
I want the lowest price RAM that will do 100Mhz with 2-2-2 cycle timings and be stable.

No..PC100 2-2-2 is not slower...maybe lower performance, but not slower in timing..
Lets do a little math...
OK...well 133Mhz is 7.5ns, at 3 cycles (cas3) is 21.5ns (yes maybe your ram is rated at 7ns, but frequency and period are inverses of each other resulting in a 7.5ns cycle time when running at 133Mhz)

100Mhz is a 10ns clock cycle (again, yes I know PC100 ram is usually rated at 8ns, but running at 100Mhz results in a 10ns cycle time) so then 2 cycles at 10ns is 20ns.

So what I am asking is this:
Mushkin Budget PC133 RAM is rated to run with a CAS active time of 21.5 nanaoseconds, by running it at 100Mhz CAS2 I would be asking it to run with a CAS active time of 20 nanaseconds.

I have absolutely NO IDEA at all how tolerant memory is for things like this, is that 1.5ns I'm shaving off the 3 timing settings going to affect the stability of my RAM?
 
Officeboy, he is not asking weather or not it is slower, he is trying to figure out if he can buy the cheaper PC-133 Case 3 and run it @ PC-100 2-2-2 and you said most definatly. How do you know it will run @ the faster latency???
 
ouch 🙁
Well looks like I'm a bit wrong there (thanks Noriaki)
Tell you what, you can getPC-150 from Mwave for $112 and it does 150 2,2,2 no problem...
But if you don't want to do that, then just try the budget 133. If it does not work then I will buy it from you. And then you can get the PC 100 2,2,2. OK
I am that sure that you will have no problem...
(There is no way that their tolerances are that tight that the PC-133 will not run at PC100, 2,2,2.)
 
Well you're not exactly &quot;wrong&quot;, PC133 CAS3 is better performance than PC100 CAS2...just doing the exact timing calculations...
But I don't know how exact it is that's all..

 
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