dual proc vs dual cpu

[bwanaaa]

is there a comparison that is accurate that anyone has seen? What would be the theoretical differences?

 

[RichUK]

i dont know but i would like to know

 

[RichUK]

i would think dual core probably

 

[imported_Otter]

I have seen no comparisons. I would expect the dual core solution to perform slightly better due to reduced latencies between the cores. This would be more pronounced with AMD than Intel, as AMD's cores are more tightly intergrated.

If you find some actual head to head tests, let us know 🙂

 

[Jeff7181]

The biggest difference is that dual cores have to share the same memory bandwidth, dual CPU's don't. Other non-performance related differences are of course heat generation and power consumption... which will be more with dual CPU's vs. a dual core CPU.

 

[TStep]

The main difference that I am concerned with is the price and selection of the motherboards. Onboard features, overclocking options, DDR options, etc, etc, etc. Dual cpu boards are usually workstation class boards costing an arm and a leg to outfit, I only need the cheaper enthusiast mainstream boards (not mission critical).

 

[Markfw]

Originally posted by: Jeff7181
The biggest difference is that dual cores have to share the same memory bandwidth, dual CPU's don't. Other non-performance related differences are of course heat generation and power consumption... which will be more with dual CPU's vs. a dual core CPU.

Exactly, except to add TStep's comments on price, yes dual-cpu is more exspensive than dual-core. Of course theres one other dual-cpu advantage, use dual-core (or quad) cores and you have 4 or 8 total cores which you can't do on a single socket mobo !

 

[TStep]

Originally posted by: Markfw900
4 or 8 total cores!

:Q.........that's reserved for you monster power user guys🙂

 

[imported_Otter]

Dual cores share the same memory bandwidth, however, there seems to be more than enough to go around with AMD's current controller, and the advantage to sharing the one controller is that either core can access all the RAM without any latency penalty. If you commonly run two bandwidth-hunrgy applications at once, the dual CPU setup would probably win, but I suspect that in many situations the tighter integration of the dual core setup will provide an edge. Of course, we're all just guessing until someone benchmarks two similar systems.

 

[Aenslead]

Latency improvements over cpu-to-cpu communications allow Dual Cores to perform up to 7% better than dual processors.

 

[imported_Otter]

This review
http://www.extremetech.com/article2/0,1558,1813748,00.asp
tests an Opteron system against an X2 and some Intel CPUs. Unfortunately for the purposes of this thread, the X2 runs 200MHz faster than the Opteron, but it's not hard to factor this out. Most of the tests show the X2 ahead of the Opteron by about the difference in clock speeds, indicating that the higher bandwidth of the dual CPU system and the lower latency of the dual core cancel each other out, at least in the few mulitasking tests they did.

If you find a better dual vs single article somewhere, please post the URL. 🙂

 

[BillyBobJoel71]

does hyperthreading count as dual core or is it really only 2 logical processors acting like 2 physical?

 

[imported_Otter]

No, hyperthreading is 2 logical processors running on one physical core.

Of course, some of Intel's dual cores also have hyperthreading for up to four simulataneous processes. They won't run as fast as on a quad core, though. In fact, in some situations Intel's dual cores do better with hyperthreading disabled.

 

[Viditor]

Originally posted by: bwanaaa
is there a comparison that is accurate that anyone has seen? What would be the theoretical differences?

Yes, some of the X2 reviews had comparisons...

Tech Report review

For the AMD dual cores, bandwidth is far less important than latency. The AMD dual core uses a crossbar for communicating between cores which takes 1 clock. In a dual CPU, the interaction takes closer to 7-8 clocks...

 

[Geomagick]

Originally posted by: Jeff7181
The biggest difference is that dual cores have to share the same memory bandwidth, dual CPU's don't. Other non-performance related differences are of course heat generation and power consumption... which will be more with dual CPU's vs. a dual core CPU.

Not true all the time.

Most Xeon systems share a FSB which is the limiting factor on the netburst architecture - hence why the better versions of the Xeon have massive L3 cache.

Some Opteron Duallies are similar. The Hypertransport from one chip goes to the other and then to the RAM. Only one memory controller is used.

 

[Fox5]

Originally posted by: Viditor

Originally posted by: bwanaaa
is there a comparison that is accurate that anyone has seen? What would be the theoretical differences?

Yes, some of the X2 reviews had comparisons...

Tech Report review

For the AMD dual cores, bandwidth is far less important than latency. The AMD dual core uses a crossbar for communicating between cores which takes 1 clock. In a dual CPU, the interaction takes closer to 7-8 clocks...

Wouldn't ASMP be better than SMP then? Cause if you have two seperate threads, I can't see any reason you'd want to switch it from one cpu to the other when they're both equally fast, but if you had many cores with each one specializing in something different, well then there might be an advantage.(but why not just add more fpus or something onto a single core?)