[X4U] Do you REALLY need matching memory in a Mini?

[Stroller]

On 26 Aug 2006, at 07:45, B. Kuestner wrote:

>> The Mac Mini appears to support dual-channel operation, which does  
>> indeed seem to be the same as "interleaving".
>
> They are not. Both features can work independently in a machine and  
> be combined.

Ah, excuse me.

> So from the link that Philip provided we know that the Mac Mini can  
> handle interleaving. But it also has dual-channel RAM access.

I wrote my reply before I saw Philip's, but it was rejected for size  
because I accidentally sent as rich text. I just resent this morning.

> So in the past you had machines that were only interleaving (old  
> Macs and some old PCs, mostly servers).
>
> Starting with newer RAM-technology, PC-makers introduced dual- 
> channels between RAM and CPU. This technology has a significantly  
> larger impact. In many circumstances (larger transfers from RAM)  
> bandwidth is effectively doubled. (Which is nowhere near the case  
> for interleaving.)
>
> <http://en.wikipedia.org/wiki/Dual-channel>

Many thanks.

I read on that page:

    Dual Channel-enabled memory controllers utilize two 64-bit data
    channels, resulting in a total bandwidth of 128 bits, to move data
    from RAM to the CPU.

And at <http://www.xlr8yourmac.com/RAM/>:

    4) Question: What is memory interleaving and what advantage does
    it provide?
    Answer: Even though the system data bus is 64 bits
    wide, the memory controller in Power Macintosh 7300, 7500, 7600,
    8500, 8600, 9500, and 9600 computers can support 128 bit data read
    and write operations by interleaving data between corresponding
    DIMMS.

This is what led me to believe they must be essentially the same. I  
thank you for your clarification.

> The test I originally referred to was a PC of almost similar or  
> better specs than the Mac Mini (Think MHz for the same Core Duo  
> CPU). But in many benchmarks it did worse and even significantly  
> worse than the Mac Mini. Main reason: The slower RAM bandwidth  
> effectively throttled both the CPU and the GPU.

In the case of different computers, I wonder where else speed  
differences could arise, however? Maybe the chipset of the Mac Mini's  
motherboard (northbridge, southbridge, whatever) is also better? I  
would prefer tests showing the same machine with a single stick of  
512meg vs 2 sticks of 256meg. For instance, this <http:// 
www.geekpatrol.ca/blog/121/> seems to be a poor comparison (despite a  
good Google rank for "matched RAM").

This note seems concise to me: http://guides.macrumors.com/ 
Matched_RAM_on_Intel_Macs
If it is correct then it is a very helpful synopsis.

Stroller.