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View Full Version : New workstation: dual E5345 (8 cores) - advice needed



Pavlov
06-02-2007, 02:52 AM
hi all,
as subject, i'm buying this 8-core machine, i'd like to know something about these CPUs since nothing can be found easily on the net.
Precisely, i'd like to know how a single processor of these stacks on "standard" and very diffuse cpus like AMD 4200 dualcore.
I'd like to make some power/pricing computations... thanks

Paolo

Captain Obvious
06-02-2007, 04:58 AM
The quad-core Intel CPUs are basically just two Core 2 Duos on a single chip. Find some benchmarks for the Core 2 Duo, and interpolate that up to eight cores instead of two (and keep in mind that nothing scales perfectly linearly).

Pavlov
06-02-2007, 05:02 AM
i found benchmarks for the processor after posting... it's very performing, BUT a test says it has limited scalability, so 2 of these perform just a 30% more than a single one. It's also true that a single XEON is much faster than a single common quad, so the machine is performing afterall... i saw some Modo benchmarks and it looks like this 8-core machine is somehow 3.5/4 times faster than an AMD 4800, which looks good. If there are other infos on this, it would be useful to hear since i'm going to place the order Monday ;)

thanks,
Paolo

Captain Obvious
06-02-2007, 09:19 AM
BUT a test says it has limited scalability, so 2 of these perform just a 30% more than a single one
Well, that's bullscrap.

We have a whole bunch of eight-core Intel machines (1.8GHz), and modo is about six times faster when using all eight cores, compared to just using one of them.

clumsycloudy
06-02-2007, 09:51 AM
I have an intel quadcore and the thing that bugs me most is that fprime only uses one processor for the first 15 seconds in previewer and fires the 3 remaining after that, with an update on the preview render that takes about 30 seconds.

ric

Captain Obvious
06-02-2007, 11:46 AM
It's not that it takes 15 seconds for the remaining threads to kick in; it's that it only uses one thread until the quality level ticker appears. I can imagine that being approximately 15 seconds for quite a few scenes, but it does vary.

But yeah, that is a little bit annoying.

Extent
06-02-2007, 05:42 PM
Well, that's bullscrap.

We have a whole bunch of eight-core Intel machines (1.8GHz), and modo is about six times faster when using all eight cores, compared to just using one of them.

Hu? Even rough estimating:

1core =1x speed
4core =4x speed
8core (4core +30%) = 5.2x speed

That's within 1 core of your 6, putting scalability at 50-60% at best. It's not awesome, but not quite bullcrap either.

Pavlov
06-02-2007, 06:42 PM
it's not that scalability on signle CPU sucks... it's multiprocessor one that does.
Honestly i'd expect 2 processor to run at least at 90% more than one, not 30%. It' WAY low, but as said a single quadcore, non Xeon processor machine is much slower.

BTW Fprime thing is bad new, i already hoped to see lighting-fast increments at startup.

Paolo

Extent
06-02-2007, 06:56 PM
It's diminishing returns. For just 2 cores it is close to 100%, but as you add more cores the % drops lower for each one. At one point adding cores would actually slow the machine down, since the mount of power necessary to manage the threads on all the cores would be greater than the power an additional core would add.

Captain Obvious
06-02-2007, 07:32 PM
Hu? Even rough estimating:

1core =1x speed
4core =4x speed
8core (4core +30%) = 5.2x speed

That's within 1 core of your 6, putting scalability at 50-60% at best. It's not awesome, but not quite bullcrap either.
FPrime and Maxwell scale better than modo, but I don't have any exact numbers to quote for them.