Question that's bothering me! =)

[jl123]

What exactly is buffered and unbuffered RAM?? And what is CAS-2 and CAS-3? And i also heard something about registered ram. What is that all about?

Thanks for all your help. I'm just trying to iron out some confusion. http://sysopt.earthweb.com/forum/smile.gif

~Joel

[desmocat]

Joel, I found this in a book I have , All it said is that buffered ram has additional buffer chips on them to interface to the motherboard. It also said that the buffer chips slow the dimm down and are not effective at higher speeds. So it sounds like not the thing to have if you are going to O/C.
As for cas2&3 this means Colunm Access Strobe. This is (I think, don't quote me. http://sysopt.earthweb.com/forum/smile.gif )
how the cpu addresses the memory. I found a link for ya to check out on it:
www.lostcircuits.com/memory/dimms3.html (http://www.lostcircuits.com/memory/dimms3.html)

It explains it pretty well. hope this helps.. MP EDIT>> your answer is about half way down the page.

[This message has been edited by desmocat (edited 07-20-2000).]

[jl123]

Ok so i sort of understand this CAS-2 and CAS-3 stuff. So CAS-2 is capable of handling speeds above 100mhz? And this buffered RAM is RAM that slows down the data flow so that the motherboard can handle it? I think i read that at some site. Please correct me if i'm wrong. http://sysopt.earthweb.com/forum/smile.gif Thanks a lot. http://sysopt.earthweb.com/forum/smile.gif

~Joel

[Glynn R Harris]

Whoa, there!
Buffering is a way of making sure that devices get their proper requirements as far as current.

If you have SIMM or DIMM, you've noticed that some of them have 4 devices per stick, or 9, or 16, or 24... (DIMM are just double-SIMMs, electrically...) Anyway, so a buffer is a extra chip that takes an Input signal and BOOSTS its strength/ability to feed multiple chips (they call it "fan-out").

It adds a Latency, meaning it does NOT slow down the clock, but an extra length of time needs to be taken into account when timing the RAM with the rest of the system and in DMA. The BIOS takes care of this latency when the buffering chips are onboard the mobo.

By the way, some very nice premium mobos have built-in buffering, and are nice O/C machines. Abit has that on their fancy boards for instance.

When the buffers are on the RAM sticks themselves, the CAS latency will need to be adjusted, and sometimes if you have two sticks, one with one latency requirement and one with another, they don't particularly mix. So Buffered and Unbuffered RAM in the same system is often a headache. But you can find either specced to similar speeds, so don't assume one is a dog and another an angel.

As memory technology improves, they improve its efficiency. Buffering may become less of a problem with RDRAM or DDR or whatever lies ahead. Or a bigger problem may eclipse the fan-out debacle; lawsuits, for instance. http://sysopt.earthweb.com/forum/wink.gif

For now, if your memory is being fed from a weak signal CMOS chipset, and you need to stuff your mobo with sticks full of chips, the buffered memory will be more reliable.

CL3, CL2 are Column-Access Latency numbers.

Memory is either RAS-before-CAS or CAS-before-RAS. Lately, all the PC stuff I see is CAS-before-RAS, meaning it takes the column signal before the row. You find a lot of R-memory for laser printers though. So now you know what the C means.

[jl123]

Thanks so much guys. I appreciate the help from you guys everytime. Thanks for taking me out from under a dark cloud. http://sysopt.earthweb.com/forum/smile.gif Hehe

~Joel

[desmocat]

Opened my eyes too.. Thanks for the info Glynn. That's the way I like it, Learn something new everyday. mmm, brain food http://sysopt.earthweb.com/forum/wink.gif