[KLUG Members] "Mix'n match" Durons/Athlons, even different speeds -- WAS: Dual Pentium Pros

[Bryan J. Smith]

[ Should probably move this to HARDWARE-only? ]

On Wed, 2002-04-03 at 11:17, Richard Zimmerman wrote:
> Word is from Tom's hardware guide that you can buy a Athalon MP
> motherboard (Duel cpu) and use Duron processors on them. Of course it's not
> officially supported but reported to work VERY well. I'm looking into this
> option myself. (HOME use, NOT office)

I have a Tyan Tiger MP (S2460), which is the "standard ATX" PS one (not
the specialized one).  I have successfully used the following combos:
- (2) Athlon-C 1.4/266      (running now)
- (1) Athlon-C 1.3/200 + (1) Duron 650/200
- (1) Athlon-C 1.4/266 + (1) Duron 866/266 (overclocked 266 FSB)

You can "mix'n match" Durons, Athlons, etc... as long as the FSB
matches.  Athlon uses the Alpha EV6 P2P bus, *NOT* the Intel GTL+ SMP
bus.  It's true "crossbar bus" (like a "network switch") between CPUs,
memory, AGP/PCI, etc... NOT "symmetric bus" (like a "network hub") so
the CPU speeds don't have to match (just the FSB).

Just like Intel's SMP processors (yes, some P3/P4s are *NOT* rated for
SMP!), all "MP" Athlons are just tested for MP, but use the
_exact_same_core_ as the uP versions.  Starting with the Athlon "XP+"
processors, AMD "locks out" MP operation with a bridge.  So you need to
either get the "MP+" version, or bridge them on the regular XP+.

> From personal experience. If your going to have a loaded system, use a
> 300 watt power supply. This way, you don't have the worries. When you have a
> loaded multimedia system (CD-ROM / CD-RW, 2hd's, etc) and only a 250w power
> supply, then PS lifetime seems to be really short (2 years) compared to when
> I used 300+ supplies.

Dual-Athlon needs a _lot_of_current_ on the 3.3+5V lines, as well as
some on the 12V.  I tried a highly rated (AMD approved) Antec PP412X
400W (a whopping 245W on the 3.3+5V!) and it did *NOT* cut it once the
system "warmed up" (as heat reduces output on most PSes).  I could hear
the CPU fans "throttling" up and down as voltage was dropping due to
current overload.  I'm sure my GeForce3 is sucking up a lot of juice,
and I have all 5 PCI slots (3Ware Escalade 6200, IOMega Buz
video/UltraSCSI, SB PCI128, 10/100 NIC, Voodoo2 12MB) populated as well.

I now have a Enermax VG-465 435W and it's working well.  Antec has a new
510W PS designed _just_ for the dual-Athlon.  I recommend a _good_ 450W+
if you put more than a few drives and cards in it.  Get
_massive_cooling_ too!  I'm using an Antec SX1000-series case (original
an SX1040 before I ripped the PS out -- the SX1000 is w/o the PS).  And
don't use the retail fansinks, get a ~$13/each Thermaltake Volcano 6Cu
(don't get the "+" -- too noisy).

With MP, you don't need the "pre-empt" patch for the Linux kernel (since
it is based on the kernel's partially-rentrant code for MP anyway). 
It's mega-responsive -- forget the benchmarks.  Because you now
basically have a CPU dedicated to user input (mouse/keyboard) at the
same time as normal usage.  That's the first thing you notice when you
go MP.

-- Bryan

-- 
  Would you trust a vendor who doesn't rely on its own products?
Ask Microsoft why it uses mainly UNIX servers and Linux providers!
------------------------------------------------------------------
Bryan J. Smith, SmithConcepts, Inc.      mailto:b.j.smith@ieee.org
Engineers and IT Professionals        http://www.SmithConcepts.com