DDR speed choices

[Samsonid]

(caution: I am Hardware novice)

Although I looked through the archives, many guys here seem to be speaking in codes so I would like someone to spell it out for me.

When we choose memory for a new board do we go with the board manufacturer's spec (say DDR400 for the A8V-D) ? or do we get a faster memory (say DDR433) and have it run slower ?

Do you guys get (out of spec) faster memory only because you overclock ?

What is the "Kosher" way of doing things for someone who wants the best performance *without* putting their system through overclocking stresses ?

Thanks
Thomas

 

[magratton]

If you are not planning on overclocking then your options for the best performance (and least amount of tinkering) would be to buy some DDR400 ram that runs CAS2 at default settings (i.e., you just plunk it in and it works at CAS2). However, if you are not benchmarking, etc. and you want something that runs decent, I would go for CAS2.5 or even CAS3. Honestly, I do not believe you will see much of a difference if you are gaming, playing MP3's, regular stuff.

Also, going for 433 or faster RAM generally it will run at faster speeds if you slow it down. I believe that most DD500 Ram (PC4000?) is the only real exception to this rule.

So in a nutshell, yeah, you typically only exceed the mobo's specs if you want to overclock.

 

[Samsonid]

Hi magratton,

Thanks for the comments.

So basically there is nothing wrong in using a DDR433 stick on a DDR400 board (without overclocking anything). It is just that we would be paying extra for nothing and the DDR433 stick will be behaving as DDR400 ?

Also, if we plan to reuse the sticks in the next motherboard upgrade is it better to get the faster mamory now so that we can carry-over the sticks to the newer board later?

 

[Steve]

That would work. And if you overclock the DDR400 FSB, the DDR433 RAM has some headroom for ya.

 

[Samsonid]

Also, going for 433 or faster RAM generally it will run at faster speeds if you slow it down. I believe that most DD500 Ram (PC4000?) is the only real exception to this rule.

Ok, here is a real life example:

What would happen (in regards to timings) if I used this stick:

Corsair DDR466(PC3700) Non-ECC Unbuffered
Cas Latency: 3-4-4-8
Support Voltage: 2.75V
Bandwidth: 3.7GB/s
Organization: two 64M x 64 -Bit
Special Features: Plug-n-Frag Auto-Configuration

and underclock it down to 400 (to match the mobo spec; instead of overclocking the mobo)

Question 1: Would this stick be able to run at lower timings (2-3-3-6) when underclocked to 400 ?

Question 2: If the BIOS was left in AUTO what would the SPD chip communicate to the BIOS ? Is it smart enough to adjust the timing of the underclocked memory without any intervention ? or will it get confused and use the worst possible settings ?

 

[Samsonid]

hmm, interesting... it was possible to answer my own question by looking here

Quetion #2 still stands though.