Single channel memory for s754 mobo

[jayoinoz]

Not sure if this Q should be in the CPU section or here (newbie).

Am I correct in saying that 754 A64s have a Single channel memory controller and 939/940 Dual channel? If so, what are the consequences of getting 1 X 1GB versus 2 X 512Mb memory sticks for my (upcoming) A64 3200+ system (mobo to be decided - DFI LANParty UT nF3-250Gb if I can find someone who'll ship one to Ireland!!!!)

I'll worry about timings another day but Ill get PC3200 memory or faster. Thanks!

EDIT: I see BW86 has answered the first part of this already in this topic. But what about 1 vs 2 sticks? Any difference/advantage?

 

[Concillian]

1 stick will overclock better in a S754 board, BUT 1GB DIMMs don't overclock well becuase they use higher density chips that don't give high speeds/very low latencies yet.

2x512 is the best bet for overclockability.

The 1x1GB will likely also be more expensive because they use the higher density chips.
If you don't care about super fast/low latency memory and you're comparing memory with the same speed and latency buy on price.

 

[MornNB]

According to AMD's specs for their memory controller, 2x512 must run at 166mhz. Now some motherboards work fine with 2x512 at 200mhz some don't (actually Asus and MSI are best for that), you'll be better off with 1GB for socket 754 because it will fall within the specifications if you want to run it at 200mhz and will be problem free.

 

[jayoinoz]

Thanks guys. I think I'll go with 2 X 512Mb and make sure the memory's decent - Ballistix or something. If I get PC3200 Ballistix, will I be able to get more that 200Mhz out of it? Should I go for PC4000 instead? I plan on attempting a bit of overclocking. My first since "squeezing" 133Mhz out of my 120MHz Pentium, alhough that was just a simple matter of increasing the multiplier. Ah, back in the day.

 

[MornNB]

If you want, but don't complain when you can't get it to work at more than 166mhz, even though it easily could.

 

[StormRider]

What does the AMD specs say about using all 3 DIMM sockets for a socket754 board? Can you run them at 166 Mhz? Or does it drop down to 133 Mhz? I have 3 spare PC2700 sticks that I'm thinking of using in a Socket754 system.

 

[MornNB]

You actually aren't supposed to do that unless they are single sided. But give it a shot it'll probably work, just depends on how well the motherboard handles stuff that's out side of the specs.
http://www6.tomshardware.com/m...memory_modules-05.html
There is a nice list here.

 

[xakuma]

I have another question about single channel and dual channel memory (sorry it's a little unrelated). Is there any difference between a stick of single channel memory and a stick of dual channel memory, by the labels they sell them as in stores? From my understanding, all "dual channel" means when referring to the sticks themselves is that they divide the size by two and give you two of them. So if a friend and I want to split a set of 1GB dual channel memory to each get a 512MB stick, should there be any problem?

 

[MornNB]

There should be no problem.

 

[jayoinoz]

That'll be no problem as MornNb says. But remember that you'll only have one Single channel stick each. It's not the memory itself that Single or Dual. Having two sticks means that both memory channels (if present - Socket 939 & 940) are used. One stick in a Dual capable system is still going to be Single channel. Sorry if this sounds patronising - it's not meant to be!

 

[MornNB]

Yes, but if it's for socket 754 which is single channel, one stick is best, because the memory controllers specifications limit it to 166mhz for 2 sticks of ram.
Getting dual ram is just stupid for socket 754 I can't stress that enough, you are quite likely to run into some problems.

 

[bunnyfubbles]

Originally posted by: MornNB
Yes, but if it's for socket 754 which is single channel, one stick is best, because the memory controllers specifications limit it to 166mhz for 2 sticks of ram.
Getting dual ram is just stupid for socket 754 I can't stress that enough, you are quite likely to run into some problems.

What are you talking about?

We also tested 2 DIMMs of the same memory and found that we topped out at 270 CPU setting (DDR540) with the TCCD DIMMs. The "Auto" setting on Hyper Transport speed seemed to handle anything we threw at the DFI without complaint.

Last time I checked 270MHz memory > 166Mhz

 

[MornNB]

What are you talking about?

The memory controllers specifications. If you are using 2 sticks of dual sided DDR 400 ram, AMD says that speed is to be limited to 166mhz. This is the specifications for socket 754.
Now it can work above the specifications, it just depends on the motherboard. But you are likely to run into problems if you try and run at 200mhz.

 

[Shimmishim]

its an issue of dual sided vs single sided memory...

single sided works fine with 2 slots populated...

with double sided, i think it'll work but you have to use 2T though and lose some performance... at least that's what i understood

 

[MornNB]

Well you can get double sided to work usually, but seeing as it's not recommended by AMD and hence some motherboards won't run it with stablity, you might run into problems.
Also, single sided ram is far harder to find.

 

[bunnyfubbles]

then just use any of several AT found that could do well over 200MHz...

 

[Peter]

Originally posted by: MornNB

What are you talking about?

The memory controllers specifications. If you are using 2 sticks of dual sided DDR 400 ram, AMD says that speed is to be limited to 166mhz. This is the specifications for socket 754.
Now it can work above the specifications, it just depends on the motherboard. But you are likely to run into problems if you try and run at 200mhz.

That, actually, is how PC3200 (DDR 200 MHz) is SPECIFIED. This is not a restriction imposed by AMD's memory controller.

More sockets, connectors, and most importantly more memory chips all have an effect called "parasitic capacitance" that screws up signal integrity.

PC3200 is intended and calculated for ONE single DIMM. Two DIMMs at 200 MHz is pushing your luck already; if they're double sided (more chips!), it's more than likely you'll have to run more relaxed timings, or even step back a speed notch.

 

[adaplant]

OT: Would it be better/faster to use 2 x 512MB in Dual Channel Mode on a MOBO with an Intel 875P chipset or 4 x 256 in Dual Channel Mode?

I realize this if off topic for this thread but I don't think this deserves it ownh thread and you guys appear to be likely to know the answer.

Thanks,

adaplant

 

[karlreading]

well im running 2*512 sticks of twinmoss ( winbond -ch-5 ) ddr 200 cas 2.5 dimms rock solid at cas 2.0-11-3-3 in my s754 chaintech mobo. they were dual channel kit from when i had a nf2 mobo. works 100% good and theres no problems with it at all. most recent mobo's wont have any issues on running 2 dimms ( and double sided as well .)

just my to-pennys worth.
karlos

 

[Orillian]

MornNB: I'm running a set of CORSAIR TWINX1024-3200 PC3200 2X512MB on my K8N-E and I currently have it running at 200 with no issues. The ram defaults to 200 on the motherboard as well, so I'm not 100% sure why you say it defaults to 166? even my motherboard manual mentions nothing about it dropping down to 166? just currious as to were you've seen that it does this? I'm curious to know why mine did not.

2,3,3,6 are the timing used as well.

Orillian

 

[MornNB]

Well what is this K8N-E? I have a K8NS-Pro.
And it really depends on the motherboard's bios, the specs say the motherboard should default to 166mhz when there are 2 sticks of dual sided ram, but some motherboards just default to 200mhz.
And are you using 2T timings?