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Help me with RAM

Small White Car

Small White Car

macrumors G4
Original poster
Aug 29, 2006
10,972
1,468
Washington DC
I have a 1st gen Mac Pro with 6 GB of RAM like this:

1 GB 1 GB
1 GB 1 GB

512 MB 512 MB
512 MB 512 MB


This isn't cutting it any more and I need more RAM. I understand buying in pairs, but beyond that I get totally confused about what's best in terms of cards matching. Which of these setups would you pick?

A)
1 GB 1 GB
1 GB 1 GB

4 GB 4 GB
512 MB 512 MB


B)
1 GB 1 GB
1 GB 1 GB

2 GB 2 GB
2 GB 2 GB

- - - - - -

A gives me an additional 1 GB over B, but is having the card be all the same an advantage worth having? I'll gladly sacrifice the extra GB if that helps it run better.

And if so and B is the answer, would you do it like that, or like this?

- - - - - -

C)
2 GB 2 GB
1 GB 1 GB

2 GB 2 GB
1 GB 1 GB


Thanks, this is an area where the more I read the less I'm certain of what to do. There's a lot of misinformation out there.
 
RAM is so cheap now, just buy 2x4gb - or better, 4x4gb (replace your 512mb sticks), keep your 4x1gb and be done with it.

You'll have 20gb of ram which is quite an upgrade.



So long as you install them in pairs, and they are all the same speed, it doesn't matter what size the pairs are - there is no performance benefit (other than having more RAM) from bigger modules.
 
throAU said:
Yeah, forgot you need ECC. Post reviewed above...
Click to expand...

Yeah, I guess they real question is just: On a RAM card, slots 1 and 2 have to match and 3 and 4 have to match. Is there ANY relationship between 1-2 and 3-4? Or do they really not give a rat's a** about what's going on next to them?

Put another way: I think option A is fine and that's what I would do except that I've read things that make me think that's wrong and B is better. Are those authors just full of crap? Or do they know what they're talking about?

I find it hard to know who to trust. (Which is why I come here!)
 
No difference.

As long as the individual pairs are matched, and all the ram runs at the correct speed rating, there is no benefit in bigger modules - or putting them in different orders.

Other than the fact that you end up with more RAM in total.
 
4 4gb sticks is $400 not $600. iRam at Newegg. I bought some and they work great at 800mhz or at 667mhz.
 
666sheep said:
OP: https://forums.macrumors.com/attachment.php?attachmentid=99178&d=1201245197
Click to expand...

WOW - You made my day with this one! Thanks, all, but I gotta say that this graphic really takes the cake. I love it.


Greg M said:
4 4gb sticks is $400 not $600. iRam at Newegg. I bought some and they work great at 800mhz or at 667mhz.
Click to expand...

I'm seeing $600 at crucial, and they're usually pretty competitive. I'm a little bothered by such a large price difference, it makes me think I'm missing something.
 
What you are missing is that Crucial have decided that as Apple no longer sell this type of RAM, they are now the premium vendor and upscale the price accordingly.
 
Small White Car said:
WOW - You made my day with this one! Thanks, all, but I gotta say that this graphic really takes the cake. I love it.




I'm seeing $600 at crucial, and they're usually pretty competitive. I'm a little bothered by such a large price difference, it makes me think I'm missing something.
Click to expand...

Crucial is $270 at Newegg.
 
Yeah, forgot you need ECC. Post reviewed above...
Click to expand...

ALL Mac Pros come with ECC RAM. That's not what makes his memory expensive. 2006-08 (1,1-3,1) models use FB-DIMMs and they cost about 3x as much as the unbuffered DIMMs used in newer models.
 
Regarding connection between Banks: If you have all the same modules (in matched pairs), you access Ram in quad-channel mode. If you have matched pairs, but of different sizes, you access Ram in dual-channel mode.

I have seen claims of quad-channel giving several hundred more points in Geekbench when compared to dual-channel, but real-world tests seem to show only little advantage (see chapter 'DUAL CHANNEL vs QUAD CHANNEL' around the middle of the page).

Furthermore you may want to consider latency. More than four modules result in higher latency (it is argued whether that is really noticeable), so unless you need more memory or get a good deal on a higher amount of smaller capacity modules you could limit yourself to 4 modules just to be on the safe side.
 
Neodym said:
Regarding connection between Banks: If you have all the same modules (in matched pairs), you access Ram in quad-channel mode. If you have matched pairs, but of different sizes, you access Ram in dual-channel mode.

I have seen claims of quad-channel giving several hundred more points in Geekbench when compared to dual-channel, but real-world tests seem to show only little advantage (see chapter 'DUAL CHANNEL vs QUAD CHANNEL' around the middle of the page).

Furthermore you may want to consider latency. More than four modules result in higher latency (it is argued whether that is really noticeable), so unless you need more memory or get a good deal on a higher amount of smaller capacity modules you could limit yourself to 4 modules just to be on the safe side.
Click to expand...

Good points except that the differences will be rather small and as you point out, not really noticeable. However, even the slowest RAM configuration will be many times faster than having to use a swap file on the HDD. Emphasis should be on as much ram as you can stuff in there with consideration to the configuration unless that gets in the way of more ram :)
 
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