CPU question...

[Singular Intellect]

I hoping to get some information, or even links to information, on the important differences between Quad-Core CPUs and Dual-Core CPUs, specifically the Intel brand (I tried looking around but can't seem to find what I'm really looking for, which is a basic breakdown of positive/negative results of upgrading, likely dependent upon your system goals).

Currently, my CPU is a Intel® Pentium® D Processor 950 Dual-Core at 3.4 GHz.

The item I'm eyeing is the Intel® Core™2 Quad Processor Q6600 at 2.4 GHz.

Now from my basic checking and understanding, the newer Quad-Core CPU has a faster FSB (1066MHz instead of 800MHz), double the cache size (8MB instead of 4MB) and it's combined clock speed is faster than the other CPU's combined clock speed by 2.8 GHz.

I'm building my system with the intention of it being a heavy gaming machine (aside from all my other uses obviously).

My initial impression is that the quad core CPU is obviously superior, but is that impression correct? Will games benefit from a Quad-Core CPU with individually lower clock speed but higher combined speed, or a Dual-Core CPU with a higher individual clock speed but lower combined speed? Or is it really up to the specific games recognizing multi core systems?

[fusion]

This is a good review that does shows the difference between a D 960 and Q6600:
Dressed Link


edit: also you should get the new quads like the Q9450:link. So yeah with a 1333MHz front bus and a lower power consumption and similar pricing, it is a better deal.

[Braedley]

This is by no means extensive (you may get something more from me later), but games really haven't leveraged multiple cores yet. They're starting to, but they have always traditionally been single threaded, procedural programs, which do not lend themselves to more than one core.

Multiple cores help when you have many programs open, or doing something that can use multiple cores, like image processing or math intensive operations.

Quad cores, right now, are for people who do some serious multitasking, are performing math operations that can be done in parallel, or are running virtual machines. Beyond that, it's hard to see any advantage.

[Darth Wong]

Even if you do serious multi-tasking, multi-cores don't always help. Video processing, for example, tends to transfer so much data back and forth from HD that the computer will run like shit even if it has a spare core sitting around doing nothing.

[Seggybop]

My initial impression is that the quad core CPU is obviously superior, but is that impression correct?

Yes, in every area. It's probably massive overkill, in fact, and you would probably do better with a newer dual core CPU.

Will games benefit from a Quad-Core CPU with individually lower clock speed but higher combined speed, or a Dual-Core CPU with a higher individual clock speed but lower combined speed? Or is it really up to the specific games recognizing multi core systems?

The only game right now that seriously benefits from more than two cores is Supreme commander. Otherwise, a faster dual core will be better.

HOWEVER keep in mind that despite being a dual core with a faster clock your current CPU is pretty crappy compared to current Core 2-based models. The Pentium D series is based on the failed Pentium 4 Netburst design. It's really hot and very slow per cycle compared to other processors.

If you want better gaming performance and you're not rendering or encoding video, you should probably get an Intel Core 2-based dual core CPU. The newer e8XXX series is the best right now, but anything would suffice. The cheapest, the Pentium Dual Core e2140 for around $60, would destroy your current CPU at stock speed, and can generally be overclocked by 100% if you wish.

[Sephirius]

to put it bluntly,
DO IT NAO


Q6600 can be OC'd to ~3.0 on all 4 cores on stock cooling.
I have mine running at 3.2 all cores stable w/ a thermaltake big typhoon.

[Sea Skimmer]

I have that processor, I’m told it is in fact inferior to a very high end single core processor for gaming performance since few games are coded to use multiple cores at all… but I sure don’t fucking notice, everything I have runs great even when I have tons of crap open in the background. I really can’t imagine you can get a better all around processor for under 250 bucks.

[Singular Intellect]

HOWEVER keep in mind that despite being a dual core with a faster clock your current CPU is pretty crappy compared to current Core 2-based models. The Pentium D series is based on the failed Pentium 4 Netburst design. It's really hot and very slow per cycle compared to other processors.

If you want better gaming performance and you're not rendering or encoding video, you should probably get an Intel Core 2-based dual core CPU. The newer e8XXX series is the best right now, but anything would suffice. The cheapest, the Pentium Dual Core e2140 for around $60, would destroy your current CPU at stock speed, and can generally be overclocked by 100% if you wish.

See, that's what I find slightly confusing and where I need to be educated.

With your example, I compared on Intel's own website, and the older 950 CPU has a significantly higher clock speed at 3.4GHz instead of the E2140 at 1.6GHz, plus the cache is 4 times bigger, and the FSB speeds are both 800MHz. They're both at 65nanometer technology...so what am I missing in the evaluation? Going solely by Intel's comparison system, the 950 looks superior on those fronts, so why isn't it? Am I focusing too much on clock speed and need to pay attention to other details that may not be as easy to find?

[Beowulf]

That's exactly the problem. Clockspeed is only useful for comparing between processors with the same architecture. The Pentium D and the Core 2 have completely different architectures, and the Core 2 can process many more instructions per clock than the Pentium D, on average.

[Singular Intellect]

That's exactly the problem. Clockspeed is only useful for comparing between processors with the same architecture. The Pentium D and the Core 2 have completely different architectures, and the Core 2 can process many more instructions per clock than the Pentium D, on average.

As I said, on Intel's website, under the Architecture comparison row for the E2140 and Pentium D 950, both were listed as "65 nanometer technology", no elaboration beyond that point.

I'm not expecting extreme detail explanations from anyone here, but any links to info where I could learn more about the important differences would be great. Obviously Intel's own site isn't helping much...

[phongn]

I'm not expecting extreme detail explanations from anyone here, but any links to info where I could learn more about the important differences would be great. Obviously Intel's own site is helping much...

ArsTechnica has a good overview of the Core Microarchitecture (used in all modern Intel designs, including the Pentium E2XXX and Core 2). If you really want to start getting into a reasonable amount of detail about how CPUs work, go read this book.

Even if you do serious multi-tasking, multi-cores don't always help. Video processing, for example, tends to transfer so much data back and forth from HD that the computer will run like shit even if it has a spare core sitting around doing nothing.

Plus, not all processing jobs are easily parallelizable: video encoding is one of the few tasks, there.

I have that processor, I’m told it is in fact inferior to a very high end single core processor for gaming performance since few games are coded to use multiple cores at all… but I sure don’t fucking notice, everything I have runs great even when I have tons of crap open in the background. I really can’t imagine you can get a better all around processor for under 250 bucks.

Games have begun to leverage two-core systems reasonably well right now and nobody has figured out how to get sky-high single-core performance.

[Singular Intellect]

I'm not expecting extreme detail explanations from anyone here, but any links to info where I could learn more about the important differences would be great. Obviously Intel's own site is helping much...

ArsTechnica has a good overview of the Core Microarchitecture (used in all modern Intel designs, including the Pentium E2XXX and Core 2). If you really want to start getting into a reasonable amount of detail about how CPUs work, go read this book.

Thank you for the links, phongn. Reading the first one now, and I'll look into that book as well.

[Ace Pace]

I'm not expecting extreme detail explanations from anyone here, but any links to info where I could learn more about the important differences would be great. Obviously Intel's own site is helping much...

ArsTechnica has a good overview of the Core Microarchitecture (used in all modern Intel designs, including the Pentium E2XXX and Core 2). If you really want to start getting into a reasonable amount of detail about how CPUs work, go read this book.

Thank you for the links, phongn. Reading the first one now, and I'll look into that book as well.

Got the book based off Phongn's reccomendation. It kicks ass.

[Singular Intellect]

Well, based upon what I've read and learned from you helpful folks, I'm practically certain I'll be getting the Intel Core™2 Duo Processor E8400 3.0GHz w/ 6MB Cache. Seems like the best choice given Quad technology is just too new for current software to really exploit effectively (particularily gaming wise), and furthermore it'll be better to upgrade to quad when it's significantly cheaper.

PS: Thanks everyone for your help, tips and links. Unless anyone else feels the need to scream at me about making a mistake in my purchase decision.

[Braedley]

Just to add to this discussion, the important number for gamers is millions of instructions per second (MIPS) for a single thread. Getting an overall MIPS number for a quad core is nearly useless, as it will be guaranteed to be bigger than a similar dual core, which will be bigger than a similar single core. If using the same architecture and running at the same clock speed, quad cores will only marginally out-pace dual cores will marginally out-pace single cores for single threads though.

[phongn]

MIPS is virtually useless for benchmarking. One should do application-specific benchmarking (e.g. games).

[Braedley]

It's a better benchmark than number of cores and clock speed...

[Uraniun235]

It's a worthless suggestion, though. Manufacturers don't advertise MIPS benchmarks on their CPUs, so you're going to have to find a review by someone anyway. But nobody does reviews based on MIPS - every worthwhile review includes a series of performance comparisons against other processors in various applications, which are far more indicative of relative performance than MIPS.

MIPS benchmarking... isn't that something that went out of fashion around the same time as the RISC/CISC debate?