Subject: RE: 586 vs 486 mem access bandwidth
To: None <nsheeley@doa.flame.org>
From: dennis <dennis@etinc.com>
List: port-i386
Date: 02/18/1996 12:12:20
>
>On 18-Feb-96 VaX#n8 wrote:
>~>~>I'm going to upgrade to a mboard with PCI, and I'm wondering if I should
>~>get a 586 (ahem, pentium) mboard since I've heard they have wider memory
>~>access buses.  Is this true, and does it make a significant performance
>~>impact?
>~>I'm considering the ASUS SP3G for a 486 board and either ASUS or Tyan
>~>(maybe Micronics) for a pentium board.  Tyan has the "nifty" IR transceiver
>~>which has a high toy factor (others probably do too).
>~>I'm not real convinced the CPU speed matters that much but I do want
>~>high bandwidth to memory.
>
>Yes, it makes and incredibly difference, in my experience.  I bought a 
>Cyrix 5x86, a product that is supposed to be closer to a 586 class machine
>than a 486.  The major difference is that the data bus on the 5x86 (cause 
>it goes on 486 class motherboards) is limited to 32 bits [instead of the 
>Pentium clas 64]  
>
>According Cyrix, it is supposed to run comparably wth a P90.  This is not
>the results I have seen, running NetBSD at least.  According to HINT,
>a system benchmark that is larger based on memory transfer rates,
>my computer is slower than a P66.  It feels like a P66.
>
>I recommend not buying a 486 class mboard, or a half-breed chip like mine.
>If AMD comes out with a competitively priced Pentium clone, there may be 
>competition, but for now I would recommend a ``genuine Intel'' product.
>[IMHO, the Cyrix 6x86 is not priced competitively]
>

This of course depends on what you're doing with the machine, and what
devices you will have in it. Every MB is different, with different memory access
rates and different bus performance.  Unfortunately, it can best be described as
a crapshoot.

db