Re: [gentoo-user] new machine : CPU : AMD FX-4100 ?

[Michael Mol]

On Sun, Jul 29, 2012 at 10:23 PM, Philip Webb <purslow@××××××××.net> wrote:
> Thanks for all the comments so far: HTH other users.
>
> I am struck by the huge difference in price between Intel/AMD :
> at Canada Computers -- a very reliable store in my experience since 2000 --
> Intel's price range is  CAD 200 - 240 ,
> AMD's  CAD 130 - 180  with an outlier FX-8150 at  CAD 220 .

AMD parts have long, long been generally cheaper than Intel parts. If
you can afford the Intel part, you either get more beef per dollar, or
more beef per watt. (Where 'beef' refers to the CPU's practical
computing power, not some meaty substance.)

Every now and then, AMD manages to upend Intel here. (Usually, by
being able to do either more work per dollar or more work per watt. I
don't think they've ever managed to upend Intel on both fronts at the
same time, but I could be mistaken.) AMD's Hammer core managed to best
Intel by changing the subject of the race to multicore, forcing Intel
to ditch NetBurst and develop Core. With Core2, Intel pulled ahead for
a while, but AMD caught up. Sandy Bridge reflected Intel pulling _far_
ahead of AMD in work-per-watt (not sure about work per dollar), and
Bulldozer is AMD's answer to that; AMD went superscalar on Intel
again, which is the same stunt they pulled back in 1999 with the
Athlon. (Same stunt, but they pulled it a different way.) I think
Athlon was the most recent time AMD pulled ahead in both work-per-watt
and work-per-dollar.

All of this is based on hazy recollection...I welcome any corrections.

> For  CAD 240 , I can buy an Intel i5-2550K, 4-core, 6 MB cache, 3,4 GHz ;
> for  CAD 130 , an AMD FX-4100, 4-core, 8 MB cache, 3,6 GHz ;
> both are  32 nm  & yes, I hear everyone saying that's irrelevant.
> CC seems to have much higher demand for AMDs :
> they have  c 3  Intels of each type in stock,  c 7  AMDs of each type
> (they're a busy store, which moves stuff quickly).

AMD parts are very popular because they're much cheaper, and because
you can very often upgrade systems in a more incremental fashion than
you can with Intel parts.

>
> I've looked at a few reviews, which reveal no special advantage for Intel.
> http://www.legitreviews.com/article/1766/1/ says :
> "entry level; half an FX-8150; best price; AMD Power Manager noticed
> the CPU was idle & put it in a low power state for power-saving;
> able to run  <= 3,8 GHz  when  1 - 2  threads are being used,
> but only  <= 3,7 GHz  if  3 - 4  threads are being used:
> running  1  thread can goto  3,8 GHz ;
> fully unlocked, so you can easily overclock it".
> http://www.cpubenchmark.net/cpu.php?cpu=AMD+FX-4100+Quad-Core
> shows FX-4100 as best value.  AMD says it's made in Germany.
>
> Do I need  > 4 cores ?  i5-2550K & FX-4100 both use  95 W
> (some of the more costly AMDs use  125 W ).

As Nikos noted, the 95W and 125W numbers are theoretical limits; the
CPU shouldn't idle anywhere close to those numbers.

Also as Nikos noted, you only "need" one core; that (and some hardware
support) is all that's fundamentally required for the a preemptive
multitasking kernel such as Linux to run properly. That said, having
multiple cores has very real benefit; if one process hangs in a
busyloop, your other processes won't feel that process's competition
quite so badly.

Really, once you get beyond two cores, it doesn't matter a whole lot
if you have three, four or eight cores; what matters in those contexts
is what each of those cores is capable of individually, and what
they're capable of in aggregate. How much each of those matters
depends on what you're using the computer for.

For most use cases, a small number (Say, 3 or 4) of cores running at a
very high GHz number will give you better results than a larger number
of cores at a lower GHz number. Exceptions exist. One such exception
would be parallel compiles.

>
> I lean towards the FX-4100 : does anyone have further advice ?

To my mind, the FX-8120 is the best part on the market right now:

http://www.cpubenchmark.net/cpu.php?cpu=AMD+FX-8120+Eight-Core

Compare that to the FX-8150:
http://www.cpubenchmark.net/cpu.php?cpu=AMD+FX-8150+Eight-Core

and the FX-4100:
http://www.cpubenchmark.net/cpu.php?cpu=AMD+FX-4100+Quad-Core

Now compare their performance-per-dollar on the larger chart:
http://www.cpubenchmark.net/cpu_value_available.html

>
> Also, some comments implied that Intels have a built-in GPU :
> if so, would that save the cost of a graphics card ?
> how would it compare to an Nvidia card ?  how reliable are the drivers ?

Nikos responded adequately on this...

-- 
:wq