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Date:      Thu, 9 Jan 1997 10:27:22 +0000 (GMT)
From:      Mark Powell <mark@salford.ac.uk>
To:        Lindsay Computer Systems <lcs@jumpnet.com>
Cc:        freebsd-hackers@freebsd.org, freebsd-scsi@freebsd.org
Subject:   Re: Can the P/I-P55T2P4 be overclocked?  In other words does it support 75 and 83MHz bus speeds?
Message-ID:  <Pine.BSF.3.95.970109095942.18913A-100000@plato.salford.ac.uk>
In-Reply-To: <199701081734.LAA18011@jump.net>

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On Wed, 8 Jan 1997, Lindsay Computer Systems wrote:
> On 8 Jan 1997 17:08:23 -0000, mark@plato.salford.ac.uk wrote:
> >>The ATX (XP55T2P4) Revision 3.0 does NOT have 75Mhz or 83Mhz settings.
> >>The P55T2P4-S has the third jumper soldered over to preclude 75Mhz or
> >>83Mhz. settings.
> >Rick, are you saying that the only board that supports 75 and 83 is
> >the plain T2P4 rev. >= 3.0? I was going to get a T2P4S for the SCSI,
> >but will get a seperate 2940UW if necessary to get the 75MHz bus speed.
> 
> Correct, only the plain P55T2P4 rev. 3.0/3.1 have everything needed to do 75 & 83Mhz,
> but I seriously doubt that a heavily loaded 2940 will perform well above 33Mhz PCI bus
> speeds.... 

Why's that? Also, what d'you mean by "well"?

> The SC-200 and the SC-875 stand a much better chance of running well at higher PCI 
> bus speeds when drives are attached that fully use their capabilities.

Not too sure on the quality of the FreeBSD drivers for the NCR though. And
I don't think the NCR 53c875 is supported at all, just 810 & 825 :(
Suppose, I could just use narrow drives instead of the wides I currently
have? 
Hmmm, I really wanted to overclock a Cyrix 6x86 P166+ to a P200+, and this
seemed to be the way to do it from other's expericence.

Do you have any idea whether the DFI G586VPS Pro (using VLSI Lunx chipset) 
or the or the MTech R534 (http://www.mtiusa.com/r534.htm), using the
Sis5571 chipset which I think I read somewhere "allows the PCI bus to be
locked at 32MHz [sic?] whatever the external clock speed", would be better
for this purpose?

> Rick Lindsay, Lindsay Computer Systems, http://www.jump.net/~lcs/
> Voice: 512-719-5257, Austin, Texas

Sorry for all the questions, Rick, but you do seem to know your stuff :)
Cheers.

Mark Powell - Unix Information Officer - Clifford Whitworth Building
A.I.S., University of Salford, Salford, Manchester, UK. 
Tel:    +44 161 745 5936        Fax:    +44 161 736 3596
Email:  mark@salford.ac.uk      finger mark@ucsalf.ac.uk (for PGP key)
<A HREF="http://www.ucsalf.ac.uk/~mark/">Home Page</A>




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