Depends on the cfm of your old fan really.
You could also do with passive cooling and use 2 case fans to cool it.

I've once replaced a stock P2 fan by cutting the fan out of the plastic holder (I kept the "fan duct" intact, only snipping 3 spots so the fan detached from the duct) which attaches to the CPU and using that very strong sticky tape to put a fan of similar side onto the duct, but I have to mention that mine was a Deschutes. Klamath runs pretty hot, your fan would need to dissipate over 40W of heat, instead of like 20W in case it were a similarly clocked Deschutes.

I suppose your Klamath has the original Intel HSF? Those sounded annoying and it gets worse once the bearings starts to wear out.

Could you give us a pic of your Klamath with the entire fan assembly attached and another with the plastic assembly removed?
Perhaps you could attach 2x 5cm fans side by side, but it depends on your particular situation. Removing the heatsink itself is usually not recommendable in case your CPU has the heatsink fins attached directly to the CPU itself.

Here are couple of pictures of the cpu. There metal case around the heat sink which I don't know how to remove. I have not been able to find out cfm of such old fan.
I was hoping it would be just a simple thing of replacing the old fan with something more quiet.

Those are a pain to get off (hate all slot cpu cases for that matter). My suggestion would be to remove the metal case or cut it open and replace 1 fan with 3 silent fans (try alIiexpress if you have time) , this will improve your cpu lifespan aswell (maybe you can even OC abit)

Do you think 1 3500 rpm fan would be enough if I underclocked the cpu? I don't really need 300Mhz for the retro games I was planning to play with the computer. I was originally building a 100Mhz pentium but then I realised I didn't have a mouse that I could use in a serial port, so I started building the pentium 2 which had motherboard with ps/2 ports. I would really prefer not to take the cpu cooler apart.

Baoran wrote:

Do you think 1 3500 rpm fan would be enough if I underclocked the cpu? I don't really need 300Mhz for the retro games I was planning to play with the computer. I was originally building a 100Mhz pentium but then I realised I didn't have a mouse that I could use in a serial port, so I started building the pentium 2 which had motherboard with ps/2 ports. I would really prefer not to take the cpu cooler apart.

Gelid Solutions Silent 5, 50mm
13 cfm
23 Db
4000 Rpm

This one and you probaby don't need to underclock it.

It's not an Intel stock HSF. Simplest is to replace the fan with one that moves at least the same amount of air and be done with it.

Thanks for the pics 😀

These were the only 50mm fans I was able to find in online shops in my country. I need to check if I find that one elsewhere.

Fractal Design 50 x 50 x 10mm Silent Series R3
6.8 CFM
19 dBA
3500rpm

SilentiumPC Zephyr 50
8.5 cfm
18.7 dBA
3500rpm

Scythe Mini Kaze
9.42 CFM
26.09 dBA
4500rpm

Tetrium wrote:

It's not an Intel stock HSF. Simplest is to replace the fan with one that moves at least the same amount of air and be done with it.

Thanks for the pics 😀

It should be the stock one because I have had it since it was new. My motherboard and the cpu is from the computer I built new around 1998 if I remember correctly.
Main problem is that I don't know how much air the current fan moves.

Baoran wrote:

Tetrium wrote:

It's not an Intel stock HSF. Simplest is to replace the fan with one that moves at least the same amount of air and be done with it.

Thanks for the pics 😀

It should be the stock one because I have had it since it was new. My motherboard and the cpu is from the computer I built new around 1998 if I remember correctly.
Main problem is that I don't know how much air the current fan moves.

What's the part number of your CPU?
I can't make it out from the pic.

All my OEM Intel slot 1 CPUs seem to have an "Intel"-branded CPU fan.

If remove upper metallic cover, than can use ordinal 80x25 mm fan, fixed it on two diagonal screws. I think, it's may be better solution.

The metal plate may be part of the metal fins bit. Some retail coolers had 2x5cm fans, I liked that one Coolermaster made. I think I did throw out the box though.

There is a part number on the metal clips, perhaps there are other bits of text or numbers hidden somewhere (though not very likely).

Titan fans of that size were kinda popular back then, but I don't remember which manufacturers used those fans back then. Iirc they were kinda cheaply made, I think the contemporary Coolermaster 5cm fans were better and I always ended up preferring those.

The CPU HSF looks very retail to me, but like been mentioned before, it may be a pain to remove it. But imo it's worth a shot, as long as you don't break anything. Retail coolers tend to be more reusable than pre-mounted boxed ones.

I went through several boxes of Slot 1 CPUs (not many CPUs each box, these take up a lot of space) but I don't have a similar HSF here.

Here is a close up picture of it.

It might also help if someone knew what kind of cfm values other fans used with this cpu had.

Tetrium wrote:

What's the part number of your CPU? I can't make it out from the pic. […]
Show full quote

Baoran wrote:

Tetrium wrote:

It's not an Intel stock HSF. Simplest is to replace the fan with one that moves at least the same amount of air and be done with it.

Thanks for the pics 😀

It should be the stock one because I have had it since it was new. My motherboard and the cpu is from the computer I built new around 1998 if I remember correctly.
Main problem is that I don't know how much air the current fan moves.

What's the part number of your CPU?
I can't make it out from the pic.

All my OEM Intel slot 1 CPUs seem to have an "Intel"-branded CPU fan.

Baoran wrote:

Here is a close up picture of it.

20170401_203059.jpg

It might also help if someone knew what kind of cfm values other fans used with this cpu had.

It's not a boxed CPU, so it never had a stock HSF. The CPU HSF must be retail, which means you can probably unmount it from the CPU (if not for outright replacement, you can give it a clean and a new TIM-job). Just be careful not to break anything.
Look for a fan that can cool at least 40W. I don't really like those fins though.

You 'could' look at the back of the old Tital fan and check the writings there. There's usually stuff like Amps there and maybe the model number of the fan itself.

MERCURY127's suggestion is a good one though. You may also opt to use 2 somewhat slower rotating 5cm fans, these should physically fit side by side.

Thanks.
I have never removed cooling from any pentium 2, so all I can hope is that I can find information on how this heat sink is removed.
I do remember the cpu came with heatsink and fan attached when I ordered the parts for the computer back then, but I don't remember if they had options to buy boxed or oem version of it.

It's probably latched kinda live how a CPU latches into a CPU socket using a lever. You could fiddle around with it for a bit, but you could opt to purchase a new Slot 1 HSF instead. The latter may be problematic though as there were several different types of Slot 1 HSFs and not all are compatible with all Slot 1 CPUs.

The easiest route may be to simply purchase another P2, preferably a Deschutes. If you need an unlocked one, your chances will be best with the 300MHz and 333MHz ones of an older manufacturing date. If you go about to underclock your Klamath, it will put out less heat anyway so you might be able to get away with a slower fan 😀

The store you bought your P2 from may (for whatever reason) have installed that HSF themselves and simply not tell you about it.

I've removed some Slot 1 HSFs in the past and the OEM ones tended to be easy to break.
There never really seemed to be a single standard to how the HSF was mounted to the CPU, so I basically just looked very carefully and started doing stuff and see what would move.

Some 'may' be clicked into place and those may break, but from first looks it seems yours may use those 2 metal-shiny levers to hold the HSF assembly into place.

Could you give us some additional pics of the numbers that are written on the 2 shiny metal bits of your HSF? It may lead to the actual part number.

just ziptie an 80mm fan onto it. a pentium 2 300 doesn't actually really need a fan and a lot of them didn't have one. you only need minimal air to go through it and a larger fan will be quieter anyway.

Both are exactly alike.

Does that also apply to klamath version of pentium 2? Wouldn't that mean also that a quieter 50mm would be enough?
It is really too bad that there is no way to monitor the cpu temperature with this cpu. Like there is no way of knowing if the old thermal paste is going bad after almost 20 years.

emosun wrote:

just ziptie an 80mm fan onto it. a pentium 2 300 doesn't actually really need a fan and a lot of them didn't have one. you only need minimal air to go through it and a larger fan will be quieter anyway.