I replace most of the noisy fans in the Stern Spike pins when they come in because they're so annoyingly loud with high RPMs.

Dialed In isn't anywhere near as bad as the Sterns, But it has three fans (power supply, CPU, head exhaust), so the noise is increased. The exhaust fan stuck to the head where it's amplified is the easiest target @ 30 annoying db. To address that, I went and got one that's rated at only 18db while keeping 80% of the airflow rating. The fan is yellow, which kind of goes with the aesthetic of the machine in a cool way. Sound problem solved.

STOCK FAN: 120mm x 120mm Sunon HAC0251S4-000U-999 120mm x 25mm square
Noise 29.6dB (A)
Airflow 55.0 CFM
RPM 1600RPM
Watts 1.9W
Amps 0.155A
Lifetime 35000 Hours @ 40 degrees C

REPLACEMENT 120mm x 120mm FAN:
Noise 18 dB (A)
Airflow 44 CFM
RPM 1200RPM
Watts 1.5W
Amps 0.10A
Lifetime 40000 Hours @ 40 degrees C

Cost $7.50.

There's still the CPU Fan and the power supply fan making noise in the head but changing this fan out made enough of a difference that I'll probably just leave it at that. If I want to trim a little more, I have an 11db fan that's taking longer to get here I might try later, but I think this change will be enough.

Original Stock Sunon Fan
Original Fan_small (resized).jpg
Replacement Quieter Fan
Replacement Fan_small (resized).jpg
Connector on PC Motherboard (you need to slide the pins from the connector on the new fan, and put them in the connector from the stock fan)
Fan Connector_small (resized).jpg

RPM reduction would not account for the large db difference, only bringing it down to like 23-24db. It would still be louder anyway because this fan uses hydro bearings, which are quieter than the stock sunon's bearings. Plus, didn't want to introduce new hardware. Just swapping fan for fan took care of the issue for cheap.

I haven't put a thermometer in there yet, but based on the Stern changeovers, I doubt it will make much difference in temp.

The hardest part with Spike is availability of the best fan. The one I used on the first ones is NLA. I have the supposed replacement. On the next Spike machine, I'll take some pictures. Changing out that terrible stock fan in the spike machines makes it so quiet you can't hear it when it comes on.

The crazier part is Stern is obviously buying the power supplies in bulk so they could EASILY ask for the better fan at the manufacturing level and the cost difference would likely be zero. No idea why they haven't done that.

Seems like overkill. Changing out the head vent fan took care of most of the noise. I probably won't do any more.

It's not an issue when it's being played. Volume takes care of that. It's when it's not being played that the stock fan noise is obvious.

That wouldn't be much better than what's in there already with 25 decibels max noise. The stock one is 29. You want to get into the mid-high teens.

Then 17dB will be even BETTER. Somewhere in the 15-17 range should be the target. I've seen hydro ones in the 12dB range, but that was after I bought the ones to fix this.

Go shopping on Alibaba, but read the specs carefully. Some of those jokers on there just cut and paste other people's specs and/or pictures. You'll figure it out after a short time browsing. While you're on there, pick up a $160 "Play Pinball Here" neon sign. Highly recommended.

Pro or Prem/LE? They're different fans/power supplies on earlier machines (pros had a big fan in the middle, prem/le had a tiny one at the top side). I think Stern has unified them now, though, but not sure when the changeover happened. I'll be swapping one out in a few weeks and will post pics.

I made a Stern-specific thread for replacing power supply fans here:
https://pinside.com/pinball/forum/topic/replacing-stern-spike-noisy-ps-fans#post-4351927