Weird RC-690 side fan issue

[Eureka]

My RC-690 has been working flawlessly and silently except for a bit of a buzz coming from the case. I traced it down to the side panel fans. I'm using regular Cooler Master 120mm fans on the side. What I noticed is that having an intake fan on the side creates a loud buzz, the single loudest noise on the idle system. I'm wondering what is causing this buzzing?

It's definitely not the contact, I can still hear a small amount of buzz if I manually hold the fan about 5mm away from the grille. I think it may have to do with the airflow going through the grille, but I'm not sure, and I don't want to make a drastic change to the case either. But this buzz is driving me nuts.

Does anyone else have this issue?

It also doesn't buzz if I use a fan controller, so I assume it might have something to do with the speed of the air or the rpm of the fan. I can't use a fan controller with the side panel fans because the cables are too short.

How can I fix this? I'm not sure if going to quieter fans will help because these fans are pretty quiet when not near the side panel.

 

[thilanliyan]

I had this buzzing as well with a modded P180 (I had 2 side panel fans installed). I found that the only way to get rid of the noise was to have it as a intake or exhaust (can't remember which). Flip the fan around and see if you get the same noise.

 

[Eureka]

It doesn't have the noise as an exhaust, so that's a possibility.

I wonder if that would have a better effect on my cooling, though. Right now I have it blowing into my CPU.

 

[Tullphan]

Think it'd help if you put a thin rubber washer between the fan & the side panel...perhaps to act as an insulator?
I had that case...had one blowing in, one blowing out on the side panel...can't remember if I had that buzzing or not.

 

[thilanliyan]

Originally posted by: Tullphan
Think it'd help if you put a thin rubber washer between the fan & the side panel...perhaps to act as an insulator?
I had that case...had one blowing in, one blowing out on the side panel...can't remember if I had that buzzing or not.

I tried that when I had the buzzing noise and it didn't work. It was airflow induced, not vibration induced.

Originally posted by: Eureka
It doesn't have the noise as an exhaust, so that's a possibility.

I wonder if that would have a better effect on my cooling, though. Right now I have it blowing into my CPU.

Is your rear fan an intake or exhaust? If you have to make the side one an exhaust then make the rear one an intake as long as your top ones are exhaust.

I think that side fan would have a bigger impact on the video card rather than the CPU wouldn't it?

 

[Eureka]

The RC-690 has two side fans, one near the CPU and one near the video card. I could make them both exhausts, but I have two top exhausts so that makes 4 exhausts. I thought its generally better to have positive pressure (is this actually true)?

On the other hand, I think I may do a window case mod, so I might not even have side fans. The system isn't extremely hot, either.

 

[thilanliyan]

Positive vs negative pressure is debatable. I prefer negative as it keeps the case less dusty in my case.

 

[zagood]

Take your fan out of the case and shake it gently back and forth. If the blade assembly freely smacks the frame (instead of being bouyed by the magnet), you need to get a new fan. Coolermaster should RMA it fairly quickly.

I'm not sure what part fails that makes this happen, but it usually occurs with sleeve bearing fans (and quite often) so an RMA is pretty easy.

-z

 

[Eureka]

Originally posted by: zagood
Take your fan out of the case and shake it gently back and forth. If the blade assembly freely smacks the frame (instead of being bouyed by the magnet), you need to get a new fan. Coolermaster should RMA it fairly quickly.

I'm not sure what part fails that makes this happen, but it usually occurs with sleeve bearing fans (and quite often) so an RMA is pretty easy.

-z

It's not the fan, it happens with three different fans, and it happens if the fan is anywhere near the fan grille. From some extra research it seems like it's the grille design.

 

[Alienwho]

My CM690 developed the same problem. it was like the fan couldn't support it's own weight and would vibrate. I just moved the vibrating fan to the bottom of the case as an intake and haven't had a problem since.

 

[thilanliyan]

Ummm...as the OP already mentioned this isn't a fan issue. I had the same issue and it was airflow induced.

 

[zagood]

Originally posted by: Eureka
It's not the fan, it happens with three different fans, and it happens if the fan is anywhere near the fan grille. From some extra research it seems like it's the grille design.

That's bizarre. Dremel and aftermarket finger guard?

 

[Eureka]

Well right now my plan is to just mod out the side panel, I'll just buy a good CPU cooler instead and that should compensate.

 

[Zepper]

The problem is the LACK of grill design! Little or no real effort or testing goes into fan grill design in cases. The Rocketfish made by Lian Li had the same problem. The 690 has a better grill pattern than most as the hexagonal cell (beehive) opening pattern is among the lowest restriction, but then they screw it up with the legs in the four corners to fit different sizes of fans - those have to go except for the holes you need to mount the size of fan you're using, and round off the end of whatever is left of that leg. One solution would be to cut out the grill metal and get aftermarket finger protectors to put over the holes. Unfortunately, just cutting out those legs probably wouldn't work as you'd have the inverse pattern of low restriction areas (where currently are high restriction areas) instead. Both SVC.com and jab-tech.com sell the standard nickel plated wire guards. jab tech also has black wire grills. There are also laser-cut grills, but those may have some of the same effect as the poorly done case-metal grillwork. A big part of the problem is how close the grill is to the blades. The inverse square law applies - twice as far, 1/4 the effect...

.bh.