Differences between opteron, athlon64, amd64, and x86_64?

[rcb1974]

This probably isn't exactly the right place for this question but I'm sure fellow Gentoo folks can answer this... My question is what are the differences between Opteron and Athlon64 CPUs? I couldn't find any straight forward answer at AMD's website. I understand that:

1) Some Opterons are designed to work in multi-CPU motherboards
2) Opterons may have larger caches than Athlon64s
3) Opterons are generally more expensive than Althon64s.

Other than that, what are the architectural differences between Athlon64s and Opterons, and how does this translate to performance? What are the die sizes for these CPUs?

Also, should the community start referring to amd64 as x86_64 now that Intel has adopted the technology? Just curious. Thanks!

[lbrtuk]

Athlon64s are simply Opterons that have had their hypertransport severed. So they can't do SMP.

Of course all the different models of Athlon64 have slight differences in what has been enabled and what has been disabled on the chip (usually bits of the cache) and the clockspeed.

Oh, and the Opteron has a memory controller for ECC RAM.

[NeddySeagoon]

rcb1974,

1) correct
2) They used to
3) Correct.

Opterons have a 128 bit data path to main memory, so to get the best out of them you need to fit memory sticks in pairs, although they will still work with 64 bit memory. Opterons need latched memory but AMD64s don't.

Opterons also have at least one pipe to the rest of the system (I forget its name) AMD64s have just the one.

An AMD 64 is a cut down Opteron.
At the same clock speed, an Opteron will be faster for memory intensive tasks, it has twice the data bst bandwidth but a higher latency.
For a CPU bound task, where memory bandwitdth is not the limiting factor, there is less to choose between them.

I don't know the die sizes but they are probably in the AMD data sheets. These 'data sheets' run to several hundred pages each, so I'' leave you to look.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

[scharkalvin]

Opteron CPU's come in socket 940 packages.
They REQUIRE ECC regestered memory ($$$$$!) and you
must add memory in dual banks (dual memory buses)
They have 3 Hyper channel I/O links.
They come in three flavors...
The 100 series are single cpus (but COULD be dual core)
the 200 series can be used in dual cpu SMP
the 800 series can be used in up to 8 way smp (there isn't
a 400 series for up to 4 way, though it was planned at one time)


Athlon64 cpu's come in three flavors:
Socket 754 have One hyper channel and One memory bus.
They can use non ecc, non registered memory.

Socket 939 cpu's have two memory buses. The can
also use non ecc, non registered memory and you don't
have to populate both banks (can run single channel).
they have a single hyper channel for io.

Athlon 64FX cpu's are either socket 940 or 939. The socket
940 units were relabled opteron cpu's. The socket 939
FX's are the same as the other 939 Athlon64's but have
more cache.

hope that helps.

[rcb1974]

Thanks guys. This is very informative and helps a lot!

[lbrtuk]

NeddySeagoon: amd64 is a generic name for the architecture, you mean athlon64.

[NeddySeagoon]

lbrtuk,

I meant that the non Opteron AMD 64 bit CPUs are cut down Opterons
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

[lbrtuk]

I know, I was just being pedantic about your terminology.

[ozbird]

[tarzan420]

another difference:

the athlon64's (not sure if all of them or just some) support frequency scaling.

The opteron's do not.
_________________
The power of Unix coupled with a pleasing interface and scores of usable desktop applications is a disgusting perversion of everything Unix stands for.

[ewan.paton]

[NeddySeagoon]

ewan.paton,

More cache doesn't help a great deal.

If say, a 512k cache gets you 85% cache hits then 4Mb isn't going to help a lot.
Both Intel and AMD know this. Large cache CPUs have a small niche where they are actually useful.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

[scharkalvin]

ALL opterions (100,200,800) have 3 hyper channels.
The 100 series have NONE that are cache coherent so they can't be used in SMP.
The 200 series have ONE cache coherent hyper channel link, so it can be used in two way smp.
The 800 series have all three that are cache coherent hyper channel links so that it may be
used in up to 8 way (or more with extra glue) SMP.
(2**1 = 2, 2**3 = 8, 2**2 == 4). Note there ISN'T a series 400 processor, they would have
2 of the hyper channel links being cache coherent. AMD decided not to make a 400 series
(though it was originally planned) since you can use the 800 series for 4 way SMP.

[Kow]

I think ALL Opteron's have 1mb l2 cache, while (I think) all Athlon64's have 512kb l2 cache. The difference between 512 and 1mb might be a bit noticeable in some circumstances, but between 1mb and 2mb there is pretty much nothing at this point (p4's have 2mb l2 cache).
_________________
-Kow

[MikeP]

[TerranAce007]

I have a mobile AMD64 3200+ in my notebook clocked at 2GHz. It is a socket 754 13nm model that can scale from 800mhz, 1600mhz, 1800mhz, 2000mhz. The 3200+ has a 1mb L2 cache. The AMD64 3000+ was about $30 less than the 3200+ when I bought the notebook, so I went with the fatser processor. Both the AMD64 3000+ and 3200+ are clocked at 2.0 GHz, however the 3000+ has a 512kb L2 cache and mine has the 1mb cache. I read that it turns out to about a 5% real world performance increase, which fits with the price difference betweent he two.

The new generation of AMD64 cpus has gone to the new 90nm (nanometer) core and has moved to socket 939. The 32bit semprons will stay at socket 754, and I read somewhere that the 32bit Athlon XPs will be ported to socket 754 as well, however I don't know the details. I would guess only the high end ones though, like 4000+ etc...

As I understand it, the AMD64 cpus are meant as desktop processors, the Athlon 64FX are for either hard core gamers or powerful workstation computers, and Opterons are for severs or rich, hardcore nerds living in their parent's basement.
_________________
It's all funny until someone gets hurt.


Then it's hilarious.

[scharkalvin]

The athlon cpu's (32 bit) are history. AMD will discontinue ALL
athlon cpu's mid year. The Semptron will be their only 32 bit cpu,
and will be available in socket A for the low end, and socket 754 and 939 on
the high end.

[d_adams]

[MikeP]

[axelmasok]

[TerranAce007]

Well I know the cpu in my laptop uses a lot of power, even when runing in powersave mode at 800mhz...

I get 1.5hrs battery life tops, even less when I run it at full-speed.
_________________
It's all funny until someone gets hurt.


Then it's hilarious.

[racoontje]

BTW, Socket 939 Athlon64 are identical to Opteron 1xx'es in terms of memory controllers, if you have the same revision (C0, CG, E)

[Adamantine]

[ewan.paton]

[racoontje]