Passive cooling tips for Pentium MMX/233?

sclawson · Post by **sclawson** » Thu Apr 08, 2004 1:15 pm

Folks, I'm doing some modding of my stepfather's ancient Gateway desktop PC, and will be installing a Pentium MMX/233 in place of the stock 166. (Hey, it's a faster chip, and only cost $6.

) I want to cool this thing passively, which I assume is fine given the low power consumption relative to more modern processors. But I've never heatsinked a plain ol' Pentium before, so I need some tips on how to do the job right...

What type of heatsink mounting does a socketed Pentium use? Will the same heatsinks I've used for PIII motherboards work here? If so, think a Blizzard Thunderbird (all copper socket 370 heatsink) with no fan will do a decent job of keeping things cool?

Anything I need to know about mounting a heatsink on a Pentium MMX chip?

Thanks all!

IsaacKuo · Post by **IsaacKuo** » Thu Apr 08, 2004 1:23 pm

I don't know any technical terms, but I've been playing with some ancient Pentium systems lately. So far, I've seen two different styles of heat sink clip--one is a metal ribbon which goes straight across the heat sink and clips onto two lugs on the middle of opposite edges. The other clip is a twisted wire which clips onto two lugs that are off center. Both of these clip styles lock onto plastic lugs which are integral to the socket piece--they don't penetrate the motherboard plane.

I've never seen a socket 370 processor or motherboard or heat sink, so I don't know how they compare.

alglove · Post by **alglove** » Thu Apr 08, 2004 3:14 pm

The Socket 7 used by the Pentium MMX has the same outside dimensions as Socket 370 and Socket A/462. Anything that you used for a Pentium III should work.

flyingsherpa · Post by **flyingsherpa** » Thu Apr 08, 2004 3:53 pm

you might want to bring a Dremel along... i recently stuck a stock hsf from my xp1600 onto an old K6-2/400. the clips fit, but back then the mobo manufacturers didn't think about modern, large heatsinks so a lot of stuff was in the way (capacitors, inductors etc). some quick work with a dremel shaved off some parts of the heatsink and it fit fine after that.

don't forget that a board that old probably has manual jumpers for the CPU voltage.

incidentally, the above hsf passively cools that chip at about 51C idle which is acceptable... though being the typical paranoid cooling freak i slapped a silent 5V 80mm fan on and it never gets above 40C now.

bobt_wa · Post by **bobt_wa** » Thu Apr 08, 2004 5:02 pm

I am assuming you made sure that the motherboard can use mmx chips. I made that mistake trying to upgrade a 166 without mmx.

I have passively cooled a P200 mmx with a stock socket A heatsink on a machine used for websurfing and my wife's recipe software. The HS would be warm but not hot.

The noise from an undervolted cpu fan may be far less than the old PSU and HD.

sclawson · Post by **sclawson** » Thu Apr 08, 2004 5:21 pm

Wow, thanks for all the good advice.

Sounds like one of these copper beasts will be my best bet. I can mount a fan with FanMate inline if necessary, but am hoping I won't need to. The only 60mm fans I've got put out a fair amount of ball bearing noise (that high pitched whine... yuck!) even when undervolted. Fortunately, the heatsink itself has a footprint matching the socket itself. At least it does with a PIII socket.

Regarding hard drive noise, that would have been pretty bad except that I'm also installing a new Samsung SpinPoint drive... convinced my stepfather that the reduced noise (not to mention superior performance) was worth the $60.

Not sure how loud the PSU is. It wasn't noticeable with all the noise from the old hard drive.

Regarding MMX compatibility, the stock processor is a Pentium MMX/166, so I don't think that will be a problem. Gotta look for a jumper, though, to see if that needs tweaking to run at the higher clock.

Incidentally, when my main rig recently bit the dust, I pulled my old Pentium Pro 200MHz box out of the closet, replaced the hard drive, plugged in a USB 2.0 card, loaded Windows XP Pro, and it works! Not the machine for graphics editing or MPEG compression, but ordinary office apps and Internet browsing works fine.

$h@d0w · Post by **$h@d0w** » Fri Apr 09, 2004 4:40 am

I had the pleasure of working with a old Pentium 233Mhz MMX yesterday and it went through the entire XP install process with just a heatsink.

This was a $2 heatsink too, about 1 cm in height and no thermal grease underneath.

We didn't realise the fan had died because the Fujitsu hard drive made so much noise

JimK · Post by **JimK** » Fri Apr 09, 2004 5:50 am

A good HS will get rid of the heat from your Pentium 233. Just make sure you have a way of geting the heat out of the case. A bit of airflow is all you need. Perhaps a Panaflo L1A at 5v?

POLIST8 · Post by **POLIST8** » Fri Apr 09, 2004 6:28 am

Seriously, I wouldn't worry about using a fan on that chip. I've unplugged many a 40mm dying fans on 200/233MMX chips in my day without overheating problems. Heck, I unplug PII 300/400 chips.

Just make sure that there is some sort of heatsink on the thing and you'll be fine - besides, if the CPU breaks I'll mail you one I have laying in my basement.

sclawson · Post by **sclawson** » Fri Apr 09, 2004 7:34 am

Oh! Just realized that I have a bunch of these laying around...

They came from MPJA, a surplus electronics house. The link to this heatsink (for 99 cents!) is over here.

The box it came in talks about mounting a fan, but there are no fan mounts. I'm hoping the long fins might suggest it's designed as a passive heatsink?

So now I'll decide between the MPJA heatsink and the all-copper Blizzard Thunderbird that I've got. By the way, here's a photo of the Blizzard (although I won't use the fan of course)...

Opinions either way with these two heatsinks... or won't it really matter?

$h@d0w, ROFLMAO!

AZBrandon · Post by **AZBrandon** » Fri Apr 09, 2004 12:44 pm

sclawson wrote:

The box it came in talks about mounting a fan, but there are no fan mounts. I'm hoping the long fins might suggest it's designed as a passive heatsink?

That's exactly what the stock heatsink looks like on my P166. Just a tall heatsink, no fan. Since it's so old that nothing had thermocouples or anything back then, I just used electrical tape to stick a radioshack thermo probe to the top/center of the sink. At idle, the end of the sink would usually be around 30C with ambient temps at 25-26C. This was with a 24" high tower case and no fans except for the PSU. At full load it would stabilize at around 55C, which is pretty hot considering it's just measuring at the top of the sink, not on the die. Still, I've heard that the old 166 could be run up to 95C, which is quite a lot hotter than anything I ever saw.

Gooserider · Post by **Gooserider** » Fri Apr 09, 2004 12:59 pm

My current box uses a pre-MMX P200, and my GF's box is an AMD K6/2-350 on both units I used the 'stock' grade annodized Aluminum HSF's with the little tiny 40mm fans, none of which have been noisy enough to be a problem. On both machines the fans have died several times w/o notice - I'd take the lid off to work on something else and notice that the fan was dead. I'd replace the fan (or usually the whole HSF) on general principles, but it seems that those chips are happy as long as there is some sort of heatsink and a moderate amount of air flow through the case.

Gooserider

POLIST8 · Post by **POLIST8** » Fri Apr 09, 2004 12:59 pm

I need ramsinks for the EDO memory that runs with my 233. Just smoooooooooooooookin.

al bundy · Post by **al bundy** » Sat Apr 10, 2004 1:52 am

sclawson wrote:

They came from MPJA, a surplus electronics house. The link to this heatsink (for 99 cents!) is over here.

That sure looks alot like the AAVID Passive heatsink selling for $9.00 over at SiliconAcoustics...

m0002a · Post by **m0002a** » Sat Apr 10, 2004 2:36 am

Years ago I had a Pentium 90 which I later upgraded to an MMX-180. Neither had any kind of heat sink or fan attached to them. Never had a problem.

sclawson · Post by **sclawson** » Sat Apr 10, 2004 10:27 am

al bundy wrote:
sclawson wrote:

They came from MPJA, a surplus electronics house. The link to this heatsink (for 99 cents!) is over here.
That sure looks alot like the AAVID Passive heatsink selling for $9.00 over at SiliconAcoustics...

al bundy, I don't want to trash SiliconAcoustics. They've got some neat stuff. But I can tell you that the box this 99 cent heatsink came in said "AAVID" on the side...

BTW, looked like the photo of the Blizzard wasn't working for some reason. DOH! I fixed it in the previous post, and here it is for convenience, the mighty all copper beast...