Dual Channel question

[Dida]

My computer has AMD CPU that uses the Venice core, I heard this thing has better dual channel support. I already have a compare of Corsair Value 2x512 MB. I would like to add another pair of 2x512 by either Corsair or OCZ. Does the 2nd pair has to match exactly with the first pair?

 

[Knight-Dragon]

No. You only need them in pairs of 2.

 

[Speedo]

You should try to use memory with the same timing though.

 

[Dida]

The 1st pair are already running in dual channel. The 2nd that I am planning to buy, albeit different from the first pair, are themsevle identical.

 

[Zelig]

The Venice has better dual channel support in that it can run 4 dimms at 400 MHz, but you will have to lower the command rate to 2t, they will not run at 1t.

If you get unmatched sticks, they should work alright at stock speeds, but they will all have to run at the speeds of the slower sticks, and you can forget about overclocking.

 

[GrandAdmiral]

If you wanna upgrade just replace your ram with a matched pair of 1gb sticks. Otherwise I think you are wasting money and possibly degrading performance.

 

[Dida]

What if my 2nd pair of rams are identical as my first pair? would that still degrade performance?

 

[Speedo]

It would probably raise the latency somewhat, but value series memory isn't ultra low latency anyway so it's not the end of the world.

The ideal solution would be to replace your current RAM with a matched pair of 1GB DIMMs, if you're willing to spend that much. I'm not sure though if value series RAM is available in matched pairs....

 

[Dida]

the 1st pair is Corsair ValueSelect, I am planning on buying another pair of the same ram, or maybe, if I don't have to buy my gf an expensive birthday gift, i will buy a matching pair of 1 gbs.

 

[GrandAdmiral]

Oh I just noticed you were using value select. If you buy 2 more of the same sticks you probably just won't notice a difference and it will still be slower then if you were to replace the entire set with a matched 512mb pro sticks from Corsair or OCZ. So if you can't afford a pair of 1gb sticks replace your existing ram with a good matched pair of pro/premium 512mb sticks. The upgrade to 2gb total ram isn't as dramatic as it is when you go from 512mb to 1gb. Once you have 1gb total ram bandwidth and latency become bigger factors then using up your total memory.

 

[Dida]

How big a role does CAS Latency play in my case? I have 2.5 CAS with my ValueSelect I think. Those XMS ones have CAS 2. How much difference is between these two? I know the XMSs cost twice as much.