Loud, and the stock 5800 isn't much better to be honest.
Not as loud, but still an annoying whine that you only associate with med\small High RPM ball bearing fans.
If you ever had a Vantec 60 or 80mm tornado fan, something like that.

I basically sat on my GeForce 2 Ultra until the GeForce 6 6800 GT came out, so I never got to experience the FX fans first-hand. What an upgrade that was. 😳

Every one after that has been pretty lackluster.

I have one of those cards but it doesn't work (bad caps maybe or dead GPU). It is loud.

Unrealistically loud (I say this because it's clipping; there's actually no reference for us to decide how relatively loud it is compared to anything else, so it's possible that you're listening to it louder than the real thing, or quieter than the real thing, etc) - that card also looks modified/hacked; there should not be a through-hole over the blower (it does not intake air from inside the case like the GTX Titan style coolers). In practice the 5800U isn't all that loud - any modern (since Radeon X) blower card will be substantially louder at full RPM, and the 5800U does not run it's fan all the time (most of the time the fan isn't even on, making it truly silent (and no, it doesn't run all that hot in passive or active mode - the heatsinks do a very good job)).

The little million-RPM screamers that used to be common on chipsets and cards like the GeForce 4 or WildcatVP are louder than the 5800's fan as well, and most never turn off.

Finally - this is recorded with the mic right on top of the card, which isn't realistic; you don't sit 2" away from the exhaust feed of your PC, do you? With the card in a case on the floor or inside a desk you will not hear the noise over even moderate level game audio (and with headphones, even open headphones, it may as well not exist).

Regarding other FX cards - I haven't owned/seen a 5950 with Flow FX II in person (nVidia reports it's supposed to be quieter though), but my 5900XT is almost silent at idle up and with light loads, but if it heats up it spins the fan faster and becomes more audible - it isn't a screamer though (it does, however, tend to run hotter than the 5800U). Neither is annoying or obtrusive unless you're setting them in a silent room and play very demanding games (which will keep them fully loaded and peak their temperatures) with no audio. Unfortunately I cannot say the same for many later blower-equipped cards.

EDIT

Went looking for, and found, a better quality video showing the fan: http://www.youtube.com/watch?v=qspdnAYiiug

The tone is right (and I would venture that it does have a relatively distinct sound), but again there's nothing to relatively give you an idea of amplitude (around 1:15 it also shuts off the fan - I have no idea what he's got going on to load/unload the card - the red LEDs are a reflection).

And of course, the obligatory nVidia response video (which never gets old 🤣):
http://www.youtube.com/watch?v=WOVjZqC1AE4

I will also add, because it may be an easier relative comparison for folks - most rack servers are substantially louder and whinier than the 5800 (and basically any other graphics card). You shouldn't assume that the 5800U is like having a server room in your office. 😊

5800,5900, 5900 ultra.
With the reference sink just take the cover off unplug the fan, and put a slot fan next to it or over it, and its nice and silent and very well cooled 😎
This is how I use them without all the noise generated.
I hate small rpm fans that produce the whine, especially ones of the 60mm variety, that run at 6k-8kRPM.
Which is why I mentioned the Vantec Tornado fan series.
A full Speed 30 watt 120MM DELTA fan will also give you a nice comparison, actually it'll be louder 🤣 .

AlphaWing wrote:

5800,5900, 5900 ultra. With the reference sink just take the cover off unplug the fan, and put a slot fan next to it or over it […]
Show full quote

5800,5900, 5900 ultra.
With the reference sink just take the cover off unplug the fan, and put a slot fan next to it or over it, and its nice and silent and very well cooled 😎
This is how I use them without all the noise generated.
I hate small rpm fans that produce the whine, especially ones of the 60mm variety, that run at 6k-8kRPM.
Which is why I mentioned the Vantec Tornado fan series.
A full Speed 30 watt 120MM DELTA fan will also give you a nice comparison, actually it'll be louder 🤣 .

In theory the 5800 Ultra could also function in that manner, but you'd have to tear the shroud apart and find a way to stabilize the heatsink's fins. It's more work than I'm willing to invest in a card that doesn't bother me (noise-wise) or run too hot for my tastes (or its own good). Basically, it works and I'm not messing with it. 😊

I'm actually curious if the 5800/5900/5900U don't get whinier than it at load though - I know the 5900XT can, and I've heard other cards with 40-60mm fans that absolutely can as well.

I replaced the stock cooler on my 5950 Ultra.

I've been tempted to order a few of those Mau1wurf1977, there what like 4 or 5$ on ebay?
But the fan on them looks like junk, is it?

Also the 5900\5900U seem to have 3 fan speed settings. A low one when it boots into windows, a medium grade at nominal load, likes to idle at this speed at the dos prompt. And of course a full speed setting when its under load.
The 5800 on the other hand only seems to do its low speed mode when not underload in windows, and full speed everywhere else even not when underload. Very intolerable for me.
Its an Asus Geforce FX 5800, it may be so its two modes maybe specific to its bios. I bought it new when it was released, and its seen heavy use through the years ironically, probably more then any other card I've owned.

Planning on doing a video about this cooler. It's basically silent and I tested it on the FX because it has a temp sensor. I got basically the same temps as with the stock cooler from Leadtek 😀

I have a few of those coolers. They really are great. I have one on a 6800 Ultra! There are some smaller versions that work nicely for older cards too.

Thats nice if the fan isn't loud. I need to replace a fan on a GF4 4400, might try one of them that fit.

I use the same cooler (but all copper) on my Quadro FX 1300; it's the same chip as the 5950 but is PCI-E and has two DVI ports. Cool as a cucumber.

I have a Zalman variant of that cooler that's got copper (or copper colored) fins in the center; it's on my WildcatVP right now, but it used to be on my 6800GT (which ran 400MHz core, but couldn't quite hit 1100 on the RAM). In both cases it's quiet (near silent) and very cool running. My only gripe with the Zalman version is it uses a normal 3-pin connector, so it can't plug into your typical graphics card. The one pictured there has a shorter lead and the right 2-pin connector, so that's a bonus imho.

AlphaWing: Interesting to hear that the vanilla 5800 never turns its fan off - does it drop clocks when it idles? Or does it stay at 400/800 all the time?

According to GPU-Z, the Asus 5800 I have idles at 300mhz 33%fan speed, Hits 420mhz when under load @ 75%fan speed.
GPU-Z is Assuming it had a fan to drive. its being cooled by a slot fan x2 80mm instead of its little screamer of a blower fan is that is unpluged from the card, and temps aren't breaking 54c under-load using furmark burn-in 800x600 windowed.
If its only hitting 75% underload, it must need to hit a high temp threshold to break into full speed.
Thats assuming GPU-Z is accurate with its fan speeds at all, on FX's.

Never mind the 54c, 20min more of furmark and its now at 58c took a bit to warm up. Still same fanspeeds reported.

Very odd - is it an OC'd model (to be at 420)? On the 5800U it idles at 300MHz and the fan is off (it can game like that too); it'll cycle the fan on and off if it's running at 400, and keeps the fan on constantly at 500 (I've yet to find a game that can keep it at 500; benchmarks can do it though).

AlphaWing wrote:

Thats nice if the fan isn't loud. I need to replace a fan on a GF4 4400, might try one of them that fit.

They are essentially inaudible.

I have some doubts about the longevity of the fan, considering these coolers cost about $4. But it's not like I run these cards much so it's not a concern for me.

That is good, that those cheap heatsinks are quiet.
As for my FX 5800 yea its Asus so OC'd from factory a tiny bit. It can\could actually hit 520-530ish IF i manually OC it, but I have not bothered to stress it in years like that. No point really especially on the Tualatin its sitting in.

AlphaWing wrote:

That is good, that those cheap heatsinks are quiet.
As for my FX 5800 yea its Asus so OC'd from factory a tiny bit. It can\could actually hit 520-530ish IF i manually OC it, but I have not bothered to stress it in years like that. No point really especially on the Tualatin its sitting in.

That 520/530 range is what my XT would top out at, and what I've read is a pretty common topping out point with the 5800U as well - seems like that's a common limit for NV3x chips perhaps...

Probably, towards the limit. I remember it was the first card I owned to break 500mhz.
Was very disappointed in it from the the GF4 4400 I upgraded from tho when I got it, barely any difference in most games I played at the time, other then being able to enable 4x AA MSAA instead of Quinqux, and use anisotropic filtering and not take a significant hit.