6 hour to decide: quad 2.93 or octo 2.26???

[mggm59]

Now for something completely different...

... may I chip in with my 2 cents?

I have had the exactly same doubts (still have, since I haven't jumped yet), and I am pondering another solution.

Knowing that:

But, once Snow Leopard hits and the apps get upgraded to take advantage of the better threading ... the Octo will become the better choice.

is wishful thinking (some apps just don't thread well, and in any case upgrades will not come out the next day after the release of Leopard (look at Adobe...), and now that it is clear that we can get at least to 16GB with the Quads, a possible solution would be:


Buy a 2.66 quad (cheaper, in between 2.26 and 2.93, should still be quite snappy)

I one or two years max up RAM at cheaper prices

At the same or later time take it to at least 3.2 GHz (and why not, an 8 core on a chip version of Nehalem or its follow-up (I DO NOT KNOW Intel's roadmap well, so I might be completely off here.... but the 3.2 is sure)

If really multicore SW hits hard, use to money you save now (a not trivial 20% of today's Mac, that might become 30 or more % of tomorrow's one) to shorten your renewal cycle (hoping the economy will be in a better shape then, if not, you'd better save money now).

Knowing that 3D/rendering/multitrack audio is not my (and our friends') main job, is there any big hole in this way of thinking????

 

[ANIM8R]

I'll chime in once again (that's my four cents now) and say I still say go with the Quad.

You're upgrading from a G4 733 - Snow Leopard will be multi threaded and your Quad will take advantage of that.

Use the money you save to buy equipment for your video and audio hobbies, such as extra hard drives (1TB = $90 on Newegg!).

Lastly, concerning the RAM...4GB to 8GB is a LOT of RAM. I see people talking about "only 16GB vs. 32GB" and, at the risk of pulling a Bill Gates here, are you REALLY going to need anything more then 4GB to 8GB in the next 3-4 years?

You've lasted with a G4 this long, I see a Quad Mac Pro with 4GB-8GB lasting you for another 4-5 years at least.

 

[Mac Husky]

Interesting calculation from another thread with the same topic:

Let's say I spend a month editing the project which is fairly common. Let's say it's a 3 minute commercial grade animation at 30FPS and the frames take 1min. to render on the 2.93 quad - that's 5,400 minutes or 90 hours or 3.75 days. If you have the 2.93 octad you can divide all those times in half. If you have the 2.66 octad you spend like 70% of those times. 70% of 3.75 days is 2.63 days. So basically you will save one day a month if you get the 2.66 octad instead of the 2.93 quad. But everything else you did that month went by faster and with less frustration on the 2.93 quad. With the 2.93 octad you get the best of both but the cost... oh my. You save now two days a month and additionally everything was edited quickly and with less frustration.

I did this everyday for 9 years (and taught the same) so this is pretty common sense to me. Pro Video editing too.

You have to ask yourself:
Is the one day a month going to be worth $1,700? (if no then the 2.93 quad is better than the 2.66 octad)
Is the two days a month going to be worth $2,900? (if no then the 2.93 quad is better than the 2.93 octad)
Is almost 10% faster editing (extra pep!) in your everyday work worth $500? (if yes then the 2.93 quad is better than the 2.66 quad)

GO FOR A QUAD

 

[MacClaus]

advise please

Quad 2,93

I do a lot of CS4, Lightroom and Capture NX.

How many RAM I should use... 6 GB (Triple-Channel) or 8 GB.

 

[Mac Husky]

Quad 2,93

I do a lot of CS4, Lightroom and Capture NX.

How many RAM I should use... 6 GB (Triple-Channel) or 8 GB.

So do I. Using Nikon Capture NX2 & Photoshop.
Also some other stuff out of Adobe Creative Suite 4 Design Premium.
Planning to do some FCE later on - but not excessive
So I think quad would be the right one for me, too.

Following this you should prefer 8 instead 6 GB RAM. But looking especially on that there doesn´t seam to be a signifikant benefit for 6 or 8 GB of RAM.
As some other apps may suffer using 4 sticks I would go for three of them (3x2=6GB) in the quad.

 

[cmaier]

So do I. Using Nikon Capture NX2 & Photoshop.
Also some other stuff out of Adobe Creative Suite 4 Design Premium.
Planning to do some FCE later on - but not excessive
So I think quad would be the right one for me, too.

Following this you should prefer 8 instead 6 GB RAM. But looking especially on that there doesn´t seam to be a signifikant benefit for 6 or 8 GB of RAM.
As some other apps may suffer using 4 sticks I would go for three of them (3x2=6GB) in the quad.

I don't believe apps will suffer from 4 sticks. Adding the fourth stick doesn't slow down the first three sticks, so any app that would end up using the fourth stick would instead force some other app to thrash to disk if the fourth stick isn't there. Only artificial benchmarks should suffer.

 

[Mac Husky]

Adding the fourth stick doesn't slow down the first three sticks, (...)

That´s wrong and it has been proven. I just can´t find a matching link.

 

[cmaier]

That´s wrong and it has been proven. I just can´t find a matching link.

I've seen "proof" both ways. My understanding of the "it gets slower when you add the fourth stick" proof, however, is that the AVERAGE speed of accessing all four sticks is lower than the average speed of accessing three sticks. In other words, after adding the fourth stick, the test did NOT limit itself to just using the first three sticks, and hence the average memory speed goes down.

So if you have a real world application that needs 7GB of RAM, and you consider two choices:

A) 3x2GB
B) 4x2GB

in the first case you access 6GB at triple-channel speed, but accessing the 7th GB requires lots of paging to disk which is thousands of times slower.

In the second case you access 6GB at triple-channel speed, and 1GB at single-channel speed (which is a thousand times faster than disk).

Heck, even if you assume that in case (B) all memory is accessed at single-channel speed (which I don't believe is the case), it's likely still faster than choice A.

 

[Sun Baked]

If you plan on speedy turn around of the machine in 1-2 years buy the Quad, otherwise the Octo is a really good value for a machine 3-5 years out.

 

[VirtualRain]

Quad 2,93

I do a lot of CS4, Lightroom and Capture NX.

How many RAM I should use... 6 GB (Triple-Channel) or 8 GB.

I think the sweet spot for RAM on a Quad Nehalem is 6GB in terms of both performance and price. In a year or so when 4GB DIMM prices drop and you have some cash burning a hole in your pocket, upgrade to (3x4GB) 12GB.

At least that's my plan.

 

[Mac Husky]

I've seen "proof" both ways. My understanding of the "it gets slower when you add the fourth stick" proof, however, is that the AVERAGE speed of accessing all four sticks is lower than the average speed of accessing three sticks. In other words, after adding the fourth stick, the test did NOT limit itself to just using the first three sticks, and hence the average memory speed goes down.

So if you have a real world application that needs 7GB of RAM, and you consider two choices:

A) 3x2GB
B) 4x2GB

in the first case you access 6GB at triple-channel speed, but accessing the 7th GB requires lots of paging to disk which is thousands of times slower.

In the second case you access 6GB at triple-channel speed, and 1GB at single-channel speed (which is a thousand times faster than disk).

Heck, even if you assume that in case (B) all memory is accessed at single-channel speed (which I don't believe is the case), it's likely still faster than choice A.

My "wrong" was only refering to your statement:

Adding the fourth stick doesn't slow down the first three sticks, (...)

Because it does lower down the three sticks at all due to changing from the faster tripple channel mode to a double channel mode, which means 25% lower clock frequenzy of the bus.
I was not saying, that apps always go slower with using 4/8 sticks instead of 3/6 - it depends.

Have a look at this again - especially memory riddle. When you use 3/6 sticks the system runs in triple channel mode (25,5GB/s) which is faster than dual channel mode (17GB/s) [sorry, have a german link only]. Now using 4/8 sticks, the whole system will lower down in the dual channel mode.

But as you already wrote, thats not the only point of interest. There ist another fact having influence on the total speed of the system. Mentioned in the abough linked test of barefeats also:

"As for memory usage, though you can only specify up to 3GB memory cache in the Performance Preference panel, Mac OS X is clever enough to grab unused memory as a virtual scratch volume instead before handing off the task to the actual scratch disk. If you are editing RAW photos with lots of layers and lots of history states, having the 8 memory slots in the 8-core Nehalem at dual-channel speeds can be better than 6 sticks running at triple-channel speeds. That's because slower memory transfers are better than really slow hard disk hits."

So some apps may benefit from using 4/8 sticks instead of 3/6 although the bus speed itself lowers down.

And at least "it's better to drop from triple channel to double channel performance than to run out of memory and start doing virtual memory disk swaps."