Questions about SDRAM

[joelau]

Hi,

I have a few queries about SDRAM, hopefully someone will be able to enlighten me.

1) What does CAS-2 or CAS-3 mean ?
2) What is 2 clock cycle vs 4 clock cycle ?

Regards.

[xortam]

Here's an excellent description of memory timings.

[superfly]

If memory serves,it has to do with the how many cycles the memory needs in order "refresh" any data that happends to be stored in the memory itself.

The less cycles it takes,the faster that very same data becomes available for use by the cpu,video card,etc....

The cas(and ras)latency is heavily influenced by the actual clock speed of the memory itself(especially if you overclock... ),any given memory may be certified to run 100/133 mhz(pc 100/133) with cas 2 latency settings.

But in either case if the memory clock speed is pushed higher,it may be necessary to increase the latency sttings to cas 3,in order to avoid data corruption.

[joelau]

Wow.. this is a very technical writeup...too bad i don't understand most of it.

Ok, let's make it simple. I'm going to shop for RAM, but my motherboard manual states that SDRAM should be non-ECC (which i understand), PC-133, CAS-3, and 7.5ns(4 clock cycle only).

How should i shop ? Any particular brands that i should be looking for ?

Thanks + Regards.

[superfly]

As far as i know,you don't need to look at either cas or cycle latency to ensure compatibility with any specific motherboard or motherboard chipset.

The factors that matter most are more trivial like:

voltage
ecc or non ecc
buffered or not

If you want to be absolutely sure that you're getting the memory that's best suited for your board,just go to their site and they'll have a list of recomended brands that they have tested to be compatible with that particular motherboard.

[joelau]

Thanks.
BTW, is Crucial a good brand to buy ?

Regards.

[Greebe]

joelau, Crucial is considered amoung the best you can buy anywhere. Their the PC133 "7E" mem ranks up there with the PC150 HSDram sold by Munchkin (Mushkin).

Do a search here in this forum on Crucial or 7E and you will find many comments on the subject.

[Greebe]

joelau, Crucial is considered amoung the best you can buy anywhere. Their the PC133 "7E" mem ranks up there with the PC150 HSDram sold by Munchkin (Mushkin).

Do a search here in this forum on Crucial or 7E and you will find many comments on the subject.

[Pace]

Hey Mike, go read the UBB primer on how to delete posts, it can come in quite handy

Hope this helps

Paul.

[joelau]

Thanks to all who helped.
And HAPPY NEW YEAR!

Regards.

[Greebe]

UBB won't fix packet loss I've been experiencing lately. I've tried several times to delete this puppy and ended giving up on it.

[paulcs]

I just went through this exercise. I can't seem to resist a free shipping deal these days.

http://www.crucial.com/index.asp?imodule=CT16M64S4D7E

Part No: CT16M64S4D7E
Price: 77.39
Description: 128MB, 168-pin DIMM.
Upgrade for: UNSPECIFIED

Line total: 77.39


Line Item Subtotal: $77.39
Freight Charges : $0.00

Order Subtotal : $77.39 + applicable shipping and tax

Paul
paulcs@flashcom.net

[paulcs]

Here's Crucial's take on memory timings, "Memory modules 101: The basics":

http://www.crucial.com/Crucial/pvtcontent/memorytype.asp?model=CT16M64S4D7E&memtype=SDRAM,PC133

Paul
paulcs@flashcom.net

[Greebe]

Lets see if that works Jord...

[Greebe]

Yes that works just dandy