PC133 still backwards compatible with PC100?

[CLTEK]

A friend of mine wants to upgrade his eMachine E-Tower 433i with more RAM and a new HD. I was looking around and saw that you can get PC133 for less money than PC100. I found some Viking 128MB PC133 RAM for $37.00 a stick. Sounds like a good deal if... *IF* it's backwards compatable.

The machine is used mainly for internet. Although he *LIVES* on the net. You know the type. http://www.PCGuide.com/ubb/smile.gif The Max RAM for the machine is 256MB with 2 DIMMS available. So... It's either 128MB or PC100 or 256MB of PC133.

Sound ok?

Respectfully, Cory

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Age and Treachery will forever triumph over Youth and Skill.

[Rick]

You should be able to run PC133 in a pc100 system with no problem.
Just make sure the Voltage is correct. IE:3.3 volts.
If the old stuff is 5 volt the new dimm's won't fit into the dimm socket

[Paleo Pete]

Yep, 133 is the maximum, not the only speed it will run. It should run at 66MHz too. Make sure the type and density are supported by the motherboard. Some boards don't support double sided chips, ECC, etc.

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[tjaymadison]

Some mobo's have a maximum 'limit per slot' constraint too.

Mine takes max 384, but 128 max per slot, so I couldn't use 1 x 256 and 1 x 128.

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"I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question."
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[Hockeye]

Yes it works great thats what I have in mine right now.

[CLTEK]

Hey Kids!

Thanks a ton for your help. I ended up just going to Crucial and getting 128MBs of PC100 for the same price as the PC133 at the other vendor.

I was looking around on the eMachines site and found that you can mix and match the various 'sizes' of RAM. In this case it will be two sticks of PC100, sizes 128MBs and 32MBs. I know this is ok to do. But I have a question...

I it ok to mix two sticks of different ratings, ie, PC133 with PC100 or PC150?

I'm new to this mixing of sizes stuff. Last I knew, you had to use two sticks of equal size. Nowadays, you can mix them up a bit. KEWL! What about latencies?

Respectfully, Big Cor

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Age and Treachery will forever triumph over Youth and Skill.

[AwARe]

Hello Cory,

Yes you can mix them,
You're only going to get the benefits from the "Slowest" Ram thats in the system though.
In other words if you have both pc100 and pc133, then your stuck with 100 for both.....
That is unless you can get the pc100 to run at 133 but most times it wont.....


[This message has been edited by AwARe (edited 05-16-2001).]

[hiredgoonz]

You shouldn't have any problems mixing them, but to clarify what aware said about only reaping the benefits of the slowest ram: your computer will run (or try to) at whatever fsb speed you set it at...as long as your ram is rated for that speed, you should be fine...and it is usually possible to run the memory a little higher than it's rated...

For example, your friend's etower probably has a celeron or k6-2 cpu, right? For the celeron the fsb would be 66mhz, so you can put any kind of ram you want in the system and unless you overclock the system it will run at 66...you won't get any benefit from pc133 over pc66 since they're both running at the same speed...

As far as latency...generally your choice is cas2 or 3...the number is how many clock cycles it takes for the cpu to access memory...on a 500mhz system, two clock cycles is 4 nanoseconds, three clock cycles is 6 nanoseconds...so setting the latency to cas2 saves you 2 billionths of a second for the first memory access, not exactly a big difference...

CAS2 ram is generally a little more expensive and your motherboard may tell you what to set the latency to as it may detect what the ram is...