Only you can decide if it’s safe or not, by monitoring the heatsink temps and also the temps on the back of the video card (the region under the GPU).

However, I would recommend replacing the cooler altogether with this one, which works great. There are also other alternatives on eBay or AliExpress.

As pictured, it will work perfectly for a long time.

Its not going to make it any quieter, or slower, but won't hurt anything.

if you want silent, buy something like this: https://www.ebay.com/itm/113948834218

Get a better aftermarket cooler, Phils computer lab showed some Zalman-inspired ones from China that would be fine.

https://youtu.be/QodrQadRUOQ

Oh yea, I used 2 of those on my voodoo 5

They are effective but do make the card use two slots.

The Thermaltake cooler on it is already considerably beefier than stock so should be ok with reduced fan RPM. It looks like it might even be actual copper instead of copper-colored aluminum.

Slowing down the fan might not be a problem, but try to check the temperature if you do that.
I think a much bigger danger with these cards is outright fan failure or the heatsink coming loose from the GPU. That's what worries me about generic Chinese coolers. *If* the heatsink attaches reliably then that part of it should be fine but I don't trust the fan. Nothing is more unreliable than a generic cheap fan.

I'd prefer a heatsink that allows attaching a standard fan from a reputable manufacturer. Looks like the one luckybob posted would allow that, but it also looks big.

Edit: It doesn't appear to work with the low noise adapter.

bloodem wrote on 2020-09-06, 05:15:

Only you can decide if it’s safe or not, by monitoring the heatsink temps and also the temps on the back of the video card (the region under the GPU).

However, I would recommend replacing the cooler altogether with this one, which works great. There are also other alternatives on eBay or AliExpress.

I would monitor the temps but I don't believe it has any sort of built-in sensor. That cooler looks like it would have the same problem because I've never used a small fan that wasn't fairly obnoxious sounding, even if it's labeled as quiet. The small Nocuta fans I have need to be used with low noise adapters, because they are pretty loud compared to the standard 120mm. In fact, I'm even using one on a Geforce 4 ti 4800se attached to the stock heatsink with a low noise adapter. It's a bit beefier than the stock fan so I was okay with it.

kolderman wrote on 2020-09-06, 06:28:

Get a better aftermarket cooler, Phils computer lab showed some Zalman-inspired ones from China that would be fine.

https://youtu.be/QodrQadRUOQ

I did get one of those awhile back but it would not install flush to the other geforce 4 I had so I didn't use it.

shamino wrote on 2020-09-06, 15:28:

Slowing down the fan might not be a problem, but try to check the temperature if you do that.
I think a much bigger danger with these cards is outright fan failure or the heatsink coming loose from the GPU. That's what worries me about generic Chinese coolers. *If* the heatsink attaches reliably then that part of it should be fine but I don't trust the fan. Nothing is more unreliable than a generic cheap fan.

I'd prefer a heatsink that allows attaching a standard fan from a reputable manufacturer. Looks like the one luckybob posted would allow that, but it also looks big.

Yeah this is how my other Geforce 4 is:

So now I may have to do the same thing with this one because it doesn't appear to work with a low noise adapter. The case I'm using is a Coolermaster N200 which has a side intake, but I'm not sure if a side intake fan alone could cool the card enough:

Was the fan loud from high rpm? Or does it make a racket because the bearings are all worn out? With old used fans, I usually peel back the sticker on the back of the fan and put a few drops of oil in the bearing. That usually solves the noise problem. These fans are not silent, but when working properly it shouldn't make an obnoxious racket.

The low noise adapter must be connected to the red/black wires, not the yellow single one. Unless the picture is intended as a joke 😀

I just cut the red wire in my Ti4200, soldered a resistor (actually two 1/4W resistors in parallel, so they won't heat up so much as one resistor would) and put a shrinkwrap on it. The resistance was in 10-30ohm range, I don't remember exact value.
It was 5 years ago when such cards were cheap and I didn't care too much about them, but it was working fine. I also solder resistors to CPU fans in all my 486-P3 boards because they don't need a lot of airflow. I wonder why old computers were so loud, probably because no one cared about ergonomics back then.

If you don't have special equipment and want to check the thermals, close the case, run some benchmarks for an hour, open the case (still running the benchmarks) and check if the heatsink is hot. If it burns your finger so much that you can't touch it is too hot, but if it's just warm then it should be OK.