Upgrading a Centris 610 CPU

[Academician]

Hey guys

I have recently become interested in upgrading my Centris 610 to the 68040 processor after hearing that the FPU actually boosted the speed quite considerably.

I wanted to know some opinions on whether or not this switch would pull me in the right direction in terms of getting my Centris 610 to be a nice smooth running machine.

I'll mainly be using it to send disk images to my Apple IIGs, but I want to play some games on it as well so improving performance by buying something that is relatively cheap is a + for me.

So far I have been able to locate these:

CPU 1

CPU 2

CPU 3

CPU 4

CPU 5

CPU 6

CPU 7

CPU 8

CPU 9

Which of these is processors I need to upgrade my Centris 610? And more importantly which one is the most performance increase for the money I will spend.

 

[Quadraman]

CPU 1 is probably best for what you need. 2 & 3 are LC's so you won't get the FPU you're looking for with them and the rest on the list are too expensive. I bought a pair of 40mhz 040's from IC-China recently and had no problems with them. It did take about 3 weeks to arrive, though, most likely due to increased security at customs.

I also found these from same seller

http://cgi.ebay.com/Motorola-68040-Processor-XC68040RC40M-02E31F_W0QQitemZ230141098167QQihZ013QQcategoryZ4663QQtcZphotoQQcmdZViewItem

40mhz! Woo Hoo!

http://cgi.ebay.com/Motorola-68040-Processor-Xc68040RC33M-00E31F_W0QQitemZ230138994740QQihZ013QQcategoryZ4663QQtcZphotoQQcmdZViewItem

33mhz

http://cgi.ebay.com/Motorola-68040-Processor-Xc68040RC33M-02E31F_W0QQitemZ230138994704QQihZ013QQcategoryZ4663QQtcZphotoQQcmdZViewItem

Another 33mhz

You're not going to see any speed increases unless you overclock the motherboard, though. Even if you don't overclock, the higher rated chips will likely run cooler at slower speeds and probably last longer and you'll have more room to play around if you do decide to increase the clock rate one day.

 

[Bunsen]

You're not going to see any speed increases unless you overclock the motherboard

Depends what you mean by "speed increases"
To whit:

A 40MHz '040 in a 20MHz machine will only run at 20MHz (so save your money and buy the slower part unless you plan to OC)

But:

The FPU in the full (not LC) '040 will speed up ... stuff ... a bit ... generally.

 

[Quadraman]

You're not going to see any speed increases unless you overclock the motherboard

Depends what you mean by "speed increases"
To whit:

A 40MHz '040 in a 20MHz machine will only run at 20MHz (so save your money and buy the slower part unless you plan to OC)

But:

The FPU in the full (not LC) '040 will speed up ... stuff ... a bit ... generally.

Yes, that's what I meant. The FPU will speed up math intensive operations and anything that depends on them, but you won't see a speedup in the rest of the CPU functions just by slapping in a faster chip without overclocking to the higher rated speed.

 

[ChristTrekker]

Quick lesson on '040 variants, gleaned from Wikipedia:

RC is the full chip

LC lacks FPU

EC lacks FPU and MMU

As others have said, the chip can only run as fast as the mobo is clocked for. A chip rated for a higher speed will let you achieve that speed reliably, if the mobo is clocked for it.

 

[Bunsen]

EC lacks FPU and MMU

= Memory Management Unit. Thusly, the EC is useless in a Mac.

 

[Academician]

Thanks for all the help and information guys, that model identification stuff will really help me narrow down my search to something both affordable and worth putting in the Centris for the performance gain I'm looking for.

-Academician

 

[Flash!]

If you havn't already..... take a poke around here: http://homepage.mac.com/schrier/mhz.html [] ]'>

 

[TylerEss]

Has anyone tried swapping a 68EC040 into a Mac? The Mac IIs don't have a (real) MMU and they work just fine, you just can't run Virtual Memory.

Does anybody know anything about the 68EC040? Is it a different die without MMU/FPU, or is it just the regular 68040 die with the MMU/FPU disabled? If it's the former, it might be a better choice for extreme overclocking, due to less heat production.

 

[Bunsen]

But what Mac would you drop it into, and how? Presumably the IIs don't have ROM support for any kind of '040, and then there are the socket problems, and RAM limits

 

[TylerEss]

I'd try putting it in a 40MHz Turbo040 and see if I could get 55MHz out of it.

The T040 is probably the best 68040 overclocking platform becuase you don't run into problems from overclocking the main system bus, such as the famous 'black screen on Mystic above 43MHz' issue.

Alternately, the Quadra 840AV might be a good choice, because the bus is already 40MHz. LC630 comes to mind as well, because it's the newest 68040 Mac (and even has remedial 68060 support).

 

[Bolle]

(and even has remedial 68060 support).

...???

 

[LCGuy]

Explain????? :O

 

[TylerEss]

(and even has remedial 68060 support).

...???

There was extensive discussion of this before the forums were lost; I guess if you get one of those 68060-in-a-68040-socket adaptors and put a 68060 in an LC630, you can get at least a grey-screen from it.

The adaptors are here: http://www.emulation.com/catalog/off-the-shelf_solutions/production-test_adapters/upgrade_motorola/

...not that anybody is going to pay nearly $500 to swap a 68060 into the LC630