I bought a 68060 revision 6 (71E41J) recently for a very good price. The rev. 6 CPU can usually do a really good overclock, often reaching 100MHz or more, which makes them very sought after and sometimes fakes are offered as the genuine version of the CPU. As I was already running an 060 in my Amiga 1200 I was not sure if it was worth swapping CPUs to gain more megaherts. The rev. 5 68060 I was running could do a 66MHz overclock but ran very hot. And a 50MHz 060 is not a slow CPU (in the world of Amiga).

Swapping 68060 CPUs in my Amiga 1200

I decided to swap CPUs because I wanted to test performance of an Amiga without a graphics card but with a fast CPU and high resolutions (like HighGFX and highres laced). Luckily removing the CPU was not a difficult task, prying on the corners of the socket it was out in less than 5 minutes ready to go into another one of my systems. Once the rev. 6 CPU was inserted into the Terrible Fire 1260 I was eager to do a test. Sure enough, it did not complain anything running at 100MHz!! (keep in mind I had a heatsink on the CPU when doing tests). Next time I will try 106MHz!!

Is there actually a noticeable difference between a 50 and a 100 MHz 68060?

Would I be able to detect any difference between a 50MHz 060 and a 100MHz 060 or would it only be noticeable in a benchmark program?

I was not too sure – When I had overclocked my 060 in my Amiga 4000TX from 50 to 100MHz I could feel that icons loaded faster, drawers just popped up, Workbench was just smoother and more responsive. But I was not sure if it was my imagination or reality.

With that said, I was surprised that my 100% non scientific mean of measuring the difference between a 50 and a 100MHz CPU in the following AGA Amiga Workbench screenmodes highres, highres laced, HighGFX @ 1024×768 (all screen modes in 64 colors) proved that there really was a difference!

Workbench had become even faster and more responsive. Running 3.1 with the stock Commodore 4 color icons, icons did not load anymore, they just popped up, almost all at once, drawers opened up instantly. The system speed by at such a high rate I had only witnessed something like this in WinUAE. What an amazing experience!

I changed background colors to 256 colors and could sense little to no slowdown from a 64 color screenmode. Sure, I have to test this more, but the early results are great, this is what base level Amiga should be like! Lets bring on 200MHz 060 (lets crowd fund it lol).

Cooling problems

Before I permanently run this computer at 100MHz I have to figure out a good cooling solution for the CPU. This rev.6 68060 runs cooler than the old rev. 5 I had in it before. But overclocking it makes it run slightly hotter. I suspect its above 50 degrees but not more than 60. I have some ideas on how to cool it down but will have to sleep on the ideas a little more before I pull the trigger on the stuff I need to build one..

I have a Terrible Fire TF1260 in my Amiga 1200. I used to have an Apollo 1240 upgraded to 060 in it and was very happy with that card (despise what other said about the card, it was very stable for me). Time marches on though and the TF1260 started to look more and more impressive, so I built one last year. The TF1260 supports overclocking by software. One comment I read was that the chances of a good overclock improved if you put heatsinks on the two CPLD chips.

Keep in mind that I had a heatsink on the 060 when doing overclocking tests. But the space between the 060 and keyboard is so tight it was very difficult finding a heatsink in my stash that would fit with the keyboard installed. I have actually not solved this yet, thus I just focused on the CPLDs and will try to solve the 060 heatsink some other day, until then it will run at 50Mhz.

The problem with the CPLD cooler is that the right CPLD need a short heatsink if you want to run a compact flash adapter over it. As you can get an impressive speed boost for the CF card by using the IDE port on the TF1260 this was off course something I would need to consider.

I had ordered these 18x18x20mm heatsinks for this exact CPLD before. The left one is the original form and the right one is the heatsink cut down and modified. I dont like to do fabricating as it gets so messy and difficult to get good results with hand tools. I will probably order a new heatsink in the correct height in the future.

Here I am test fitting the heatsink.

And here it is secured to the chip. I use a thermal pad from AlphaCool that I cut to fit myself. The thermal pad from AlphaCool is somewhat thicker than what you usually get when you order heatsinks from Aliexpress. The thicknes is 0.5 mm, the thermal pad is also softer and more gooier than regular flat thermal pad. Once secured with the AlphaCool thermal tape, these pads wont go anywhere, they are secured very firmly. I highly recommend these AlphaCool thermal tape and would use them even on the 060 with a large heatsink without no problem or worry that the heatsink would fall off (even if mounted vertical!)

So here we are, everything fits now. But to use the IDE port on the TF1260 I need to burn a custom Kickstart with ehide.device, more on that when I will get to it.

And about finding a solution for cooling down the 060? I have not got a clue, I will probably need to cut down a thin copper plate and place a heatsink on it offsett from the CPU. Not ideal, but better than nothing. A small heatpipe cooler leading heat to fins over the top of the cards close to the floppy drive would be ideal, but prototyping a cooler like that would take weeks and lots of money. I will see what I will come up with.