RE: 755C Processor Upgrades

[peter machule <machule@triumf.ca>]

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From: 	Angus[SMTP:afh1@ukc.ac.uk]
Sent: 	Thursday, March 06, 1997 3:04 PM
To: 	thinkpad@cs.utk.edu
Subject: 	Re: 755C Processor Upgrades

peter machule wrote:
> 
> I believe this one had an official upgrade path in form of a small pc board
> with a 75Mhz DX-4 on it.
> Of course you already have it (grin).
> Your best bet is therefore to find some kind soul who has done this and
> beg the the old 50Mhz version of him/her.
> Then buy the $45 AMD 5x86 133 and unsolder the old............

I *heard* that TP's use surface mount chips. I was considering an
upgrade but that kinda put me off. I guess that AMD are going to charge
more for the surface mount 5x86 too. Still - if you know someone who's
got the tools for doing surface mount work then that's a neat idea.
Yes the TP's use a surface mount cpu. Last time I checked the AMD 
surface mount version was $10 more?? It will  have more to do
with supply and demand than an official price list.

> OR talk to the 2 or 3 laptop upgrade companies .....I believe that two of
> them even lurk around here.  pepsales??

They charge about $300-400 last time I checked. Seems expensive for
fitting a chip that costs $45, but they got their reasons.
 
TP motherboards cost $600 to $1200 or more . This is for the 486 versions.So whatyour paying for is labour and "oops"insurance.....plus profit. ;-}

> The official prices for the 50 and 75Mhz boards are amusing
> Note: your cost could very low if you can find an old board.

Well I'm happy to swap my 50MHz board for your 75MHz - well of course
I'd pay a bit! But I don't see why the 'extra' board is needed except
for in case 'something goes wrong'...
That is why you want to do it this way. !!
 
> BTW don't expect a big improvement . You have no external cache so don't
> believe anyone quoting much more than 20% SYSTEM Performance improvement.

With a 133MHz chip versus a 75MHz? Even if you have plenty of RAM for
the OS you are using?
The AMD will only run @100 Mhz since the Motherboard clock appears to be 
fixed at 25 Mhz. The reason to use the 133Mhz rated part is for lower power
consumption and it usually doesn't cost more. Also it appears that both the 
701 and the 755 do NOT implement the Write Back cache capability of the
i486 DX4-75. Sticking in the AMD won't change that. Software might though.
If someone knows otherwise re WB cache I'd love to hear so.
again see Gainberry (whose www address I can't find now...sigh)
...peter..