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RAM Max supported 333 mhz but you use 400 mhz

What happens then?



8:18 pm on Jun 8, 2006 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member

What happens if you mother supports DDR memory 333 mhz and you put a 400 mhz...
The motherboard pdf says pc2700 is top supported but the hardwarde provider offers a 400 mhz and says it's ok.
I'm afraid he's only trying to sell something I can't use.


6:12 am on Jun 9, 2006 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member

It should be fine.

Your motherboard needs to talk to RAM at a speed not less than 333Mhz. So getting memory BELOW that speed is a problem. If you put in faster RAM, then your RAM won't be a bottleneck. It won't operate any faster than 333Mhz, but it should work.


2:41 pm on Jun 9, 2006 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member

Do I understand correcty?
Asus P4S533-X specifications:

Supported RAM Technology SDRAM, DDR SDRAM
RAM Installed ( Max ) 0 MB / 2 GB (max)
Supported RAM Speed PC2100, PC1600, PC2700, PC100, PC133

As far as I know maxiumx supported according this data is PC2700 which I belive is 333 mhz.

In fact, I'm using a slower type of memory now, but the provider says a 400 mhz would work.

Do you mean the 4000 mhz it will work but at 333 mhz, slower but safely?


2:54 pm on Jun 9, 2006 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member

The chip speed indicates that the circuits in it can operate correctly with speeds up to that rating. So a 400mhz ram chip should work okay at slower speeds.

The speed at which the computer will try to drive the chip is determined by the clock signal coming from the motherboard. In your case that is 333mhz.


3:28 pm on Jun 9, 2006 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member

So it's ok though I will not be taking advantage of those extra 66 mhz, because it will work at 333 mhz though, in a different motherboard would work at 400 mhz, correct?

AND IT'S SAFE, my motherboard will not explode or suffer any damage right? :)


3:33 pm on Jun 9, 2006 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member

Your motherboard will communicate with your DDR400 RAM at DDR333 rates. There is nothing at all to be concerned about. This is a very common configuration.


4:38 pm on Jun 9, 2006 (gmt 0)

WebmasterWorld Senior Member jtara is a WebmasterWorld Top Contributor of All Time 10+ Year Member

Well, it's a bit more complicated...

First of all, nothing is going to blow up or be damaged. There is no harm using higher-speed memory than a system calls for.

But the mHz speed rating of memory, these days (probably for the last 10 years...) is just a convenient marketing term. The actual specification consists of a number of different ratings (perhaps a half-dozen or so) for various aspects of a memory access cycle. This is too complicated to explain to consumers, so manufacturers tag a mHz rating on it.

Pick 10 different "pc2700" modules from different manufacturers, and they are likely to each have a slightly different set of specifications. That's why there are "premium" brands or lines within a manufacturer. The most common differene in premium memory is a small number of cycles for "CAS latency".

A small ROM on the memory module is read by the BIOS, and is read to determine the specifications. The BIOS then sets-up the chip set to optimally match those specifications.

A higher-speed memory than required for a given system CAN, to some degree, offer some memory speed improvement. This may require manually setting one or more memory parameters in your BIOS setup.

For example, if you use a higher-speed memory than is required, you can often change the CAS value, say, from 3 to 2, even though the memory is rated for CAS 3. The thing is, it's rated for CAS 3 at a higher speed than you are running it at, so it can be safely run at CAS 2 at a lower clock rate.

The converse is not necessarily true. A "premium" brand of memory that is rated CAS 2 will not necessarily run at a higher speed than it's mHz specification by derating it to CAS 3.

Of course, it's all a black art, since there are a half-dozen or so different specifications to juggle, and many of them interact. Gamer sites engage on endless discussion of this subject...


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