Choosing the right DDR2 memory for my PC.

[spikeyLoki]

Hello,
I'm planning to add additional memory for my PC which is DDR2. But when i went to the store they asked me what frequency without asking if it's 512MB or 1GB. I just left the store after that. I looked online and there's this same prize and memory size but different number code of something under. For example:
DDR2 800 / PC6400,
DDR2 667 / PC5300,
DDR2 533 / PC5300..
All of these are 1GB and same prize. What's that 800/PC6400 means? Can anyone help me with regards to this? Thanks in advance!

 

[rdc85]

If u dont known what u need usually i will go with higest clock speed that is DDR2 800 / PC6400

It will / can downclock automatically to 667 or 533

edit: 800 / 667 / 533, well u can think is as data rate / clock speed / bandwith, it's not exact meanings but that the general idea...

 

[spikeyLoki]

Hi! So it's doesn't matter either i buy the 800 or 667 one? Because i'm planning to buy a Kingston 2GB 800 DDR2. Currently my PC has 512MB DDR.

 

[spikeyLoki]

If u dont known what u need usually i will go with higest clock speed that is DDR2 800 / PC6400

It will / can downclock automatically to 667 or 533

edit: 800 / 667 / 533, well u can think is as data rate / clock speed / bandwith, it's not exact meanings but that the general idea...

Hi! So it's doesn't matter either i buy the 800 or 667 one? Because i'm planning to buy a Kingston 2GB 800 DDR2. Currently my PC has 512MB DDR.

 

[aggawk]

That is correct yes.

 

[bruce555]

The 800 is faster. Are you buying the 2GB as a set (2 memory sticks) or as one stick?

Either way make sure you take out your old 512mb stick (DIMM) because if you leave it in it will increase the latency between the memory DIMM's and will slow your computer down.

 

[knightdog56]

Just go to the crucial website and use the memory advisor. You can find out what size,type and speed your computer is compatible with.

 

[rdc85]

short answear yes get the 800 (frequency),

edit: since they all in same price i don't think there any reason to buy 667 or 533 one (since the 800 also capable to run in 667 / 533 speed)

 

[spikeyLoki]

The 800 is faster. Are you buying the 2GB as a set (2 memory sticks) or as one stick?

Either way make sure you take out your old 512mb stick (DIMM) because if you leave it in it will increase the latency between the memory DIMM's and will slow your computer down.

Hi! bruce555,

The 2GB DDR2 i'm planning to buy is just 1 stick. Really? I need to take out the 512MB DDR1 if i will going to out 2GB DDR2? Didn't knew that. Thanks!

 

[spikeyLoki]

Best answer selected by spikeyLoki.

 

[bruce555]

Hi! bruce555,

The 2GB DDR2 i'm planning to buy is just 1 stick. Really? I need to take out the 512MB DDR1 if i will going to out 2GB DDR2? Didn't knew that. Thanks!

Sorry for taking too long but yes, it will allow the system to run faster. Check it out yourself but you will see.


Allot of people will have the tendency of keeping mismatched sticks in at the same time and it does destroy you're systems latency.


If they were the same size (each 1gb or something) and same speed but different manufacturer's you'd would probably be fine. But that's why they package 2 RAM sticks together, they've been tested and the manufacturer knows that they are Dual Channel compatible.

 

[rdc85]

I don't think latency could be an issue, this what i'm disagree with bruce555. In normal usage or old system different latency make system slower correct. but in every day usage the impact will minimum....

we are talking much different when we are type that O.C. That increase in timing maters a lot for O.C. -er, even we admit impact of O.C. -ing the memory just give minimum performance upgrade (I don't get that kind of felling from the OP)....

anyways thanks for the best answer

 

[bruce555]

Three things must be true in order for 2 mismatched sticks to work:

1) They both must work at the designated speed of the lower stick. In your case, both sticks must work at DDR333 (166mhz). Typically there is never an issue with a DDR400 stick being clocked at a slower rate. However, there can be, which is point 2:

2) They both must work at the same timings at the designated speed as detected by SPD. The motherboard will automatically what timings to use for the sticks, but there is no guarantee that the faster stick will operate properly at the timings assigned to it at the lower speed. You have roughly a 90% chance of success here though, so don't worry.

3) The sticks both must be compatible with the motherboard. Provided 1) and 2) are true, as long as the sticks work with the board you should be good to go. Because these are of such different size, do not put them in a dual-channel configuration.

However, a question. Why? The difference between 512mb and 620mb is going to be minimal at best, and you are sacrificing a considerable chunk of memory bandwidth in doing so, especially with a P4.

I would advise not doing it from a performance standpoint.

Quote from http://www.techspot.com/community/topics/different-speed-of-ram-sticks-will-it-damage-the-motherboard-or-other-parts.30473/



It usual practice to not run dissimilar RAM in a system and only advised if it's atleast the same size/speed.

Even though the comment/issue quoted above deals with older DDR tech / P4 system, same thought applies here. It's not worth have a 2.5Gb system over a 2.0Gb for what it'll cost you on the latency/bandwidth side.

 

[rdc85]

Because RAM latency important in DDR days, not so much in DD2, DD3. apps today had much more optimized....

but, I'm guess slow or fast for each person is different.. there simple test for OP to try with both 2.5 gigs and 2. gigs and decide which one more suitable for its everyday use..

btw. I would put the slow/old ram into first slot and newer in second slot (2.5 gig configuration).
one newer in slot one and let the second slot empty (in 2 gig configuration).
Some OEM mother board rather picky....