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ScanDisk
August 13th, 2017, 03:06 PM
Hey,

My main and most beloved vintage machine has a 286 processor.

Weirdly, there is no cooling at all, neither a heatsink nor a fan.

It runs fine, and is apparently A-okay.

I know that some processor didn't require a fan, and a heat sink was sufficient, so I am wondering, was there an age in when processors did not need cooling? and would a 286 be of this age?

smbaker
August 13th, 2017, 03:21 PM
I think the first machine I recall that I owned that required a CPU fan was a Pentium. I think I had 386 and 486 that didn't come with a passive heat sink. IIRC most power supplies of that era had a fan, and that fan did provide airflow for the case. So you could argue the machine as a whole had cooling, even if not directly for the CPU.

At one point, I had a 386 motherboard and associated cards sitting on a shelf of my closet, no case, running a node for my BBS. Not even air flow cooling from the power supply.

krebizfan
August 13th, 2017, 03:28 PM
A heat sink is not needed on a 286, at least not at normal operating frequencies. One can get away without using a heat sink typically up through 486-33.

If you have an infrared thermometer, check the temperature on the chip. If it gets very hot like 60+ degrees C, you may want to place a heat sink on it. The maximum operating temperature of Intel 286 chips is 70 C while some of the other brands could take it all the way to 85 C.

lutiana
August 13th, 2017, 04:12 PM
You do not need a heatsink or a fan for most 286 processors. However, adding a heatsink or heatsink+fan would not hurt anything. The 286 in my 5170 get's really hot as well, and I am considering putting just a heatsink on it

Unknown_K
August 13th, 2017, 06:52 PM
There were 286/25's they must have been roasting with no heatsink. Fastest 286 I have is a 16 or 20 no heatsink.

Caluser2000
August 13th, 2017, 07:18 PM
My Zenith Z286LP Plus 286/12 runs fine without a heat sink.

Xacalite
August 13th, 2017, 08:02 PM
Vast majority of 286 CPUs I encountered was without any heatsink.
But there were occasional exceptions.

Chuck(G)
August 13th, 2017, 10:25 PM
Yup, passive heatsinks weren't uncomoon with some 286 systems. I've seen CLCC 286s with a little "chimney" attached to the top plate of the socket.

Heat is the enemy of things electronic--if you can get rid of it, it will extend the life of the components.

ScanDisk
August 14th, 2017, 04:53 AM
So I take it, that with my 12mhz 286, that can be 6mhz when turbo is on, I don't have any reason to care about cooling?

krebizfan
August 14th, 2017, 05:18 AM
So I take it, that with my 12mhz 286, that can be 6mhz when turbo is on, I don't have any reason to care about cooling?

Cooling should not be an issue. Keep the system clean to permit airflow and the 286 should still have a long life ahead of it.

dieymir
August 20th, 2017, 01:14 AM
I have a 286@12 NMOS that got really hot during operation. Since it's a plastic encapsulated CPU (plastic is an insulator) I wasn't confident enough to simply put a heatsink on top of it. What I have done is use an old Pentium fan with molex conector and fix it with duct tape in front of the processor to increase the airflow over it. Temperatures have lowered a lot. I have done the same with all my 386s, but those are CMOS CPUs so the benefits are smaller.

Chuck(G)
August 20th, 2017, 05:51 AM
If you were of a mind, you could replace that NMOS 80286 with a CMOS 80C286--you can find the Intersil ones(IIRC) in speeds up to 25MHz.

daver2
August 20th, 2017, 06:50 AM
I use 8 MHz 286 CPU chips on an Intel iSBC286/10A. They do not require a heatsink, but there is a minimum airflow requirement to dissipate the heat. The CPU chip does get hot though!

Dave