Opteron Vs. Athlon X2

[Bryan J. Smith]

On Mon, 2005-12-05 at 19:35 -0500, Peter Arremann wrote:
> E6 stepping has better memory timing capability (400 with a higher number of 
> memory banks)

Huh?  All Socket-939/940 processors have 4x 32-bit banks (2x 64-bit DDR
channels).  FYI, Socket-754 + 184 (2nd DDR channel traces) = 938.  ;->

> and improved power saving. E3s overclock better though :-D
> The board you've got is a 939 pin socket and will not accept dual core cpus or 
> opterons (socket 940).

FYI, the new dual-core Opteron 165 and 175 are Socket-939.  They use
unregistered DDR SDRAM, just like any other Socket-939 processor.

> Not really that much. In fact, because of the slower memory timing of socker 
> 940 opterons (registered memory adds latency) the performance improvements 
> from the larger cache are mostly negated according to our tests.

Agreed, but if you're going with a Socket-939 Opteron 1xx, then that's
not an issue.

> No - Socket 940 (most opterons) and 939 (some 1xx opterons and Athlon64) are 
> not compatible. The 939 1xx opterons that are out now are nothing more than a 
> relabeled Athlon64 X2 anyway. 

Huh?  Not exactly true, especially since some are E5 and others are E6.
And there _are_ the thermal differences.

> I would recommend the X2 over two 2xx single core opterons. You can reuse your 
> memory if you choose to. You will save yourself money on CPU and memory. Your 
> motherboard will be cheaper. The opterons will be louder because of the addl. 
> fans. 

Not if you get the "HE" single core versions that use only 55W.  The
Opteron 246HE is virtually _no_ premium over the older 246.  The Opteron
250+ are the newer steppings.  You'll have twice the number of memory
channels and width.

But from a cost perspective, I agree.

> If you're thinking of a single 1xx 939 opteron you might have a hard time 
> finding a board with support for it (two months ago I could barely find any 
> boards that were certified for it). It will run anyway just fine on 99% of 
> all 939 boards that work with the equivalent X2.  

Agreed.  The value of the Socket-939 Opteron 1xx is really the new,
entry-level server mainboards built for it.  We've talked about the
SuperMicro here.

> On the other side, if you go for dual 2xx opterons and you pay extra for a 
> good board, you get a huge improvement on IO. Multiple PCI-X busses and the 
> like are nice to have on most servers but for a developers workstation it 
> doesn't really matter.

As long as you don't need more than 100MBps in disk and network.
Otherwise, PCI-X is still much better because most desktop mainboards
only ship with PCIe x1 channels outside of video.


-- 
Bryan J. Smith   mailto:b.j.smith at ieee.org
http://thebs413.blogspot.com
------------------------------------------
Some things (or athletes) money can't buy.
For everything else there's "ManningCard."