1 GB dimm or 2x512 MB dimms?

[wraith3k]

I'm putting together a lower-end AthlonXP system for someone and also an Athlon 64 for myself..both systems will have 1 GB ram, and I'm wondering whether it is better to buy a single 1 GB dimm or 2 512MB dimms.

Someone told me that dimms have to be installed in pairs (because of dual-channel issues), is this right?

Also, stability is important, so if 2x512 is more stable, I'd go with that. But if they are equally stable I'd rather get a single dimm so I have more room to expand.

The Athlon XP will probably be using the Asus A7N8X board and the 64 will most likely have the MSI NEO FIS2R board.


thanks all

 

[Sniper991122]

not sure about your board, but it seems must have 3x dimm slots now? So im not sure how you could do 2 pairs of 2...

anyways, i was about to put together a computer with an athlon 64 and 3x dimm slots, i was just going to use 2 512's... 2 512's by crucial with error correcting was $280, 1gb stick by crucial without error correcting is $350... So you'd be paying an extra $70 there and losing ecc just in that?

economically, 2 512's...

 

[wraith3k]

You're right in that most boards have 3 slots, so I'm pretty sure I can get away with adding one dimm at a time.

I'm not sure quite sure what they mean by dual-channel.

 

[Nickel020]

For the Athlon XP you should get 2 sticks as dual channel will work only then. For the Athlon 64 it doesn't really matter as the socket 754 A64s don't support dual channel.

Edit: Dual channel means that the RAM is connected to the norhthbridge via two channels instead of only one which increases bandwidth and thus performance (I think the performance increase is something like 5%).

 

[wraith3k]

Originally posted by: Nickel020
For the Athlon XP you should get 2 sticks as dual channel will work only then. For the Athlon 64 it doesn't really matter as the socket 754 A64s don't support dual channel.

cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

 

[Nickel020]

Originally posted by: theslug
cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

As far as I know you can install 3x512MB and dual channel will still work.

 

[JustAnAverageGuy]

Originally posted by: theslug

Originally posted by: Nickel020
For the Athlon XP you should get 2 sticks as dual channel will work only then. For the Athlon 64 it doesn't really matter as the socket 754 A64s don't support dual channel.

cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

Quantity is often better than quality when RAM is concerned.

Obviously, as long as it's stable, etc.

 

[Matthias99]

Originally posted by: Nickel020

Originally posted by: theslug
cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

As far as I know you can install 3x512MB and dual channel will still work.

Or even 2x512 + 1x1024, or 2x1024 + 1x512, or 3x1024. However, these 'unbalanced' dual channel configurations offer less of a performance benefit. As the boost on the AthlonXP is pretty small for most real applications (since RAM bandwidth is rarely the limiting factor -- it's more often latency, which DC doesn't help with), this is not a huge deal.

 

[wraith3k]

Or even 2x512 + 1x1024, or 2x1024 + 1x512, or 3x1024. However, these 'unbalanced' dual channel configurations offer less of a performance benefit. As the boost on the AthlonXP is pretty small for most real applications (since RAM bandwidth is rarely the limiting factor -- it's more often latency, which DC doesn't help with), this is not a huge deal.

Would these same configs work on the A64?

 

[Nickel020]

Originally posted by: theslug
Would these same configs work on the A64?

Yes.

 

[wraith3k]

Originally posted by: Nickel020

Originally posted by: theslug
Would these same configs work on the A64?

Yes.

With DDR400 I know I can only have a 2 GB maximum (with the current A64 boards), but are you saying I could still do say 1x1024 + 2x512? It'd be 2GB but using all 3 slots.

 

[Davegod]

btw also note on nforce2 (athlonxp) there's only 3 dimms, BUT even here a lot of motherboards only allow 2 to be used at 400mhz, to use all 3 it has to be 333fsb (or something, cba digging out manual).

 

[batmanuel]

Originally posted by: theslug

Originally posted by: Nickel020
For the Athlon XP you should get 2 sticks as dual channel will work only then. For the Athlon 64 it doesn't really matter as the socket 754 A64s don't support dual channel.

cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

Dunno why they went for 3 slots instead of 4 on the NF2 boards, but you can install the RAM so you have 2 smaller sticks and one bigger stick in dual channel. I did this for a while on my A7N8X Deluxe with 2x256MB sticks in the two slots that are close together (these two slots make up one channel) and 1x512MB stick in the third slot (the one that is seperated from other other two slots by a small gap to indicate that it is the slot for the second channel). Not the most elegant RAM config, but it worked. The performance increase was noticable on benches like the SANDRA memory bandwidth test, but it wasn't all that noticable in normal apps and games.

 

[wraith3k]

Originally posted by: batmanuel

Originally posted by: theslug

Originally posted by: Nickel020
For the Athlon XP you should get 2 sticks as dual channel will work only then. For the Athlon 64 it doesn't really matter as the socket 754 A64s don't support dual channel.

cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

Dunno why they went for 3 slots instead of 4 on the NF2 boards, but you can install the RAM so you have 2 smaller sticks and one bigger stick in dual channel. I did this for a while on my A7N8X Deluxe with 2x256MB sticks in the two slots that are close together (these two slots make up one channel) and 1x512MB stick in the third slot (the one that is seperated from other other two slots by a small gap to indicate that it is the slot for the second channel). Not the most elegant RAM config, but it worked. The performance increase was noticable on benches like the SANDRA memory bandwidth test, but it wasn't all that noticable in normal apps and games.

So would occupying all 3 slots would still give dual-channel performance, say 2x512 and later on adding 1x1024?

 

[Woodchuck2000]

Three slots are only meant to be used when quantity of ram is more important than speed - the speed of the RAM almost always must be dropped going from two to three sticks so any dual-channel benefits are negated anyway.

Having four slots would increase the complexity of the motherboard and require the RAM to be run at even slower speeds to maintain stability.

Three slots is the optimum trade-off between Speed, Max RAM and Complexity.

 

[Whitedog]

Originally posted by: theslug

Originally posted by: batmanuel

Originally posted by: theslug

Originally posted by: Nickel020
For the Athlon XP you should get 2 sticks as dual channel will work only then. For the Athlon 64 it doesn't really matter as the socket 754 A64s don't support dual channel.

cool, thanks. But if this is the case, why do some Athlon XP boards have only 3 slots? Wouldn't the third slot always be unused then?

Dunno why they went for 3 slots instead of 4 on the NF2 boards, but you can install the RAM so you have 2 smaller sticks and one bigger stick in dual channel. I did this for a while on my A7N8X Deluxe with 2x256MB sticks in the two slots that are close together (these two slots make up one channel) and 1x512MB stick in the third slot (the one that is seperated from other other two slots by a small gap to indicate that it is the slot for the second channel). Not the most elegant RAM config, but it worked. The performance increase was noticable on benches like the SANDRA memory bandwidth test, but it wasn't all that noticable in normal apps and games.

So would occupying all 3 slots would still give dual-channel performance, say 2x512 and later on adding 1x1024?

I believe it's been answered already/. Yes.

With 2 memory sticks populating the "dual channel" slots, does matter if you add more or not, THOSE two sticks will be opporating in dual dhannel mode, while the other not.

 

[Whitedog]

Originally posted by: Woodchuck2000
the speed of the RAM almost always must be dropped going from two to three sticks so any dual-channel benefits are negated anyway.

Not correct. When you use all 3 slots, the mobo still runs the 2 in dual channel mode... ...And the system uses those memory addresses first before using the 3rd slot.

If the 3rd module you add runs at the same speed/timings, then there is NO performance lose.

 

[wkwong]

2x512, you can utilize dual channel which is a bit faster if your motherboard supports it.

when it comes to ram, you always get better profrmance from spreading them out rather than having all the memory goto 1 stick.