AM2, X2, Opteron, or Opteron Socket F?

[Bryan J. Smith]

On Sat, 2006-08-19 at 21:52 -0400, Robert L. Cochran wrote:
> At first, I liked Intel Core 2 Duo, but the motherboard selection doesn't 
> seem great and it is very pricy.

The price is worth it in computing power.  Core is the first, _full_
Intel x86 redesign since the Pentium Pro.  The NetBurst (P4) was a quick
refit of extending the pipes and doing virtually _no_ refactoring in the
ALU/FPU design (long story).

I still don't recommend Core 2 Duo or even Intel's forthcoming dual-FSB
processor for more than 2GiB on a server.  Some may differ with me, but
offsetting the limitations with lots of L2/L3 cache doesn't go far
enough.  They need a true interconnect and I/O MMU's on-processor.

> Then I looked at socket 939 procs...I love them...but they can't do DDR2 
> memory.

Huh?  Socket-AM2 (new 940) is just the Socket-939 with DDR2.
What's DDR2 do for you?  Not much.

The reason why AMD switched to DDR2 had more to do with consumer as well
as integrator/OEM memory cost.  E.g., I'm sure Dell balked at the idea
of going AMD when it had to keep separate memory options.

> I'm also confused by the advantages of Socket F,

Socket-F (LGA-1207) puts the pins on the mainboard instead of the CPU,
since the Socket-F processors often cost more than the mainboard.  There
are other electrical advantages as well.  AMD merely decided to
introduce an LGA option for Opteron when it went DDR2.

> socket 940 (which I know allows DDR2 memory),

Do _not_ confuse "old" 940 Opteron with "new" 940 (AM2) Athlon 64.

 DDR:  754, 939, old-940
DDR2:  new-940 (AM2), 1207 (F)

> and the advantages of Opterons over Athlon 64s or Athlon 64 X2.
> Or vice versa.

It's now 2 years old, but here is my figure for interconnect and
associated table of aggregate front-side throughput:  
  http://www.samag.com/documents/sam0411b/0411b_f4.htm  
  http://www.samag.com/documents/sam0411b/0411b_t1.htm  

The DDR2 options don't really do much as far as performance, although
memory throughput does increase.  There are also now only 1.0GHz
HyperTransport but even 1.4GHz HyperTransport 2.0 options now in the
LGA-1207 (Socket-F).

Opteron definitely tests to better tolerances than Athlon 64, and is
multiprocessor.

> I need to do some heavy, heavy database programming and website building in 
> the next 2 years. I want quick ethernet controllers.

Then buy quality Ethernet controllers, especially ones with RX (not just
TX) TCP Off-load Engines (TOE) that have full Linux support.  I've been
playing with LeWiz Communications solutions -- because they have broad
platform support.  Their low-profile PCIe x8 4xGbE starts at under
$1,000.

I didn't know about them until LinuxWorld Boston (back in April):  
Server Hardware at Linux World:  
http://thebs413.blogspot.com/2006/04/server-hardware-at-linuxworld.html  

> I'll be working mainly 
> on a Linux platform, Fedora Core or possibly Red Hat Enterprise Linux.
> What AMD processor and motherboard would work best for me? Should I focus on 
> Opterons?

For servers, they might be worth a few extra bucks in full ECC support.
They are required for multiple sockets -- especially when I/O is more
important than computational.

> One last note -- my old system has an Asrock DualSATA-939 motherboard 
> running the 2.20 BIOS. I took out the old ATI 9700 All-In-Wonder (AGP) video 
> card and put a BFG GeForce 7600 GT OC in the PCI Express slot. It works 
> great and powers my wife's 24" flat panel monitor at 1920 X 1200 resolution.

The 7600GT is a great buy right now.

If you want a high-performance, passively cooled video, the 7600GS is
also nice and can be had for $90.  It's great for set-top boxes because
of its built-in HDTV output and video decoding support in MPlayer.


-- 
Bryan J. Smith          Professional, technical annoyance
mailto:b.j.smith at ieee.org    http://thebs413.blogspot.com
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