Which processor would yield better performance for audio and video encoding/transcoding: Athlon 64 or Opteron (100 or 200) series? and where does the Athlon 64 FX come into play vs. the other two (or three)?

i realize there could be a dramatic difference between the Opteron 100 and 200 series; correct me if i'm wrong. also, is the Opteron 100 only available in single-processor configurations?

The data from Tom's hardware indicates that unless you have a lot of extra cash laying around, the Athlon 64 is your best best. The 64FX and Opteron's are quite a bit more expensive.

I believe for the most part that ddrawley (referencing Tom's) is absolutely correct. However, for some bandwidth limited applications there may be a real advantage to using the FX/Opteron processors because they possess a 128bit memory interface rather than 64 bit, effectively doubling memory bandwidth.
The socket 940 processors (Opty, FX) do require registered ("buffered") RAM, which is more expensive and introduces some degree of latency which the normal socket 754 A64 does not suffer from.

The Opteron 100 series is single processor only, while the 200 series is dual capable, etc. The third number i.e., 148 indicates the relative performance (based upon clock speed) of the processor. The only difference between the 100 and 200 series is that the 200 series has an additional hypertransport interconnect enabled. An Opteron 146 and an Opteron 246 run at the same clock speed and are functionally identical in every way excepting the fact that the latter can take advantage of the Opteron's phenonmenal multiprocessing capabilities (Assuming a motherboard with exclusive RAM access) in a dual processor setup.

thank you. price is definitely a consideration. though on pricewatch.com the lower-end opterons seem to be rather affordable.

They are indeed quite affordable. I'm seriously considering a dual Opteron system dedicated entirely to compression, serving, distributed computing, and storage.
Now I just need to stop buying CD's and saving the money instead

Note that you must install RAM modules (DIMMs) in pairs for the Opteron and Athlon FX platforms to take advantage of the 128 bit memory bus.
The A64 obviously doesn't have this issue.

Audible's explanation is very helpful and poses some points I had not considered. I had read, but had forgotten, that the Opterons utilize a 128bit memory interface.

It seems that with enough funds available a dual 200 series setup would be a powerhouse machine, as anyone would have expected. And from what I can see it would not cost an ungodly amount of money.

Tell me, please: Why the problems with memory latency when using the registered/buffered RAM?...

I highly doubt the encoding process will benefit from SMP ( multiple cpus.) The software MUST be written to take advantage. You could have a thread running on each cpu. The old formula I am aware of is %80 of the sum of the two cpu clock rates. This is the true efficiency of sharing the agp/pci chipset and ram. SMP is simply not cost effective for the average user. The money can be put in to higher clock rates of CPU and additional ram. Though more than 512Mb ram is typically not needed. These are of course generalizations.
In my personal experience, I went from dual 550Mhz cpus to a single 733Mhz. My primary day to day tasks were benefitted most by the single 733Mhz cpu.

For audio encoding, it's better to have one as-fast-as-possible processor. Many video encoders, on the other hand, make good use of a second CPU. The new Real encoder, for example, typically loads both my CPU's at 95% when encoding.

As for Athlon 64 vs. Athlon FX (or Opteron): judging from this graph from the Tech Report's review of the Athlon FX, you get almost no performance increase in multimedia encoding by moving to the wider memory bus, at least not with the applications they tested. The FX51 and A64-3400+ are both 2.2GHz, and they perform almost identically. The Pentium 4 is significantly faster in their tests for both audio and video.

Dual processors are nice on a machine you will be interacting with constantly, because the machine is so responsive and so resistant to slowdowns or lockups. But if it's just a dedicated audio encoder, you might as well just run a single CPU and save some money. If you plan on doing a whole lot of video encoding, you might want to look into dual CPU's after all. Perhaps a even a dual Xeon machine would suit you. Try to find benchmarks for the programs you intend to run.

That's my humble opinion!

What he said

Edit:

This thread is probably applicable.

AMD vs Intel for encoding

The cheaper opterins might be multi processor capable, but they are also much slower then an Athlon 64. I'd get the Athlon 64 3000+ or 3200+ (little performance difference, when you look at the price difference).

Registered RAM by definition adds latency to memory accesses. Typically this doesn't matter much since the chipset -> chip connection introduces a significant amount of latency, however since the memory controller of the A64/Opty/FX is on the processor dies itself and is designed to be extremely low latency, this is not insignificant.
Compare the benchmark results from the FX @ 2.2GHz to the A64 at the same clock speed: the additional latency essentially cripples the FX to the extent that it's nearly pointless to buy unless your applications are bandwidth limited but relatively insensitive to latency (latency is related to effective bandwidth, so this is probably somewhat rare).



Precisely Audio encoding is rarely SMP enabled, so you have to run multiple parallel instances if you want to do more in less time. Luckily current CPUs are quite fast at audio encoding. As SometimesWarrior said, video encoding tends to take longer and often is SMP optimized. Hence, a dedicated video compression SMP box is not a complete waste of time, and think of the Folding possibilities!

edited spelling

Audible,

Thank you for your explanation. I understand the latency effects now, and it's certainly a shame this has to somewhat cripple the FX CPU's.

(To anyone):

Do XviD, DivX, etc. run multiple, even two, simultaneous threads (in which case they would benefit from a multi-CPU or hyperthreading setup)? Or is this maybe done by the actual encoding app, such as VirtualDub?

Maybe I should be asking some of these questions on Doom9 instead.

I think both would have to support it (i.e. Codec could use two processors in compression, App could use to processors in filters, etc.). IIRC VirtualDub is not Multi-Thread capable. Back in the glory days, FlaskMPEG was multi-thread (although I wouldn't recommend using it now ).

Abput FX's and latencty, Socket 939 FX's (hopefully coming soon to a computer retailer near you) will not require resitered RAM and therefore not have any latency problems. However, they are obviously not out yet. Both the A64 and the FX are moving to S939 so you may want to wait on buying a new chip, as your upgrade options will be very limited.