Fan direction query

[DougMcDonald]

Hi Guys,

I know this should be pretty obvious, but is there any simple way to check what direction a fan is blowing if it doesnt have any arrows on it?

I think the airflow is my case is a bit rubbish because i can drop 5-6 degrees on the CPU temp by removing the side. I then started looking at how the flow was going, as the case itself is relatively cramped.

I have a Lian-Li PC-60A Plus II (if you scroll to the bottom of this link, you can see how the airflow around the cpu is designed to work http://www.lian-li.com/product/produ...index=4&type=a )

From that diagram is looks like there is an intake at the back, which goes through the metal guide thing (currently detached due to having a scythe infinity attached) and then out the top.
The problem is that this fan does seem to spew air in both directions, one seems a little stronger, and that would match up with the original case diagram on the lian-li site. Is it normal to see some air spray out in both directions of a fan?

Originally, I was under the impression that the fan on the back was an exhaust, but I now think it's an intake. If it IS and intake (which it looks like, then i have been running as per the diagram the below)



The red rectangles are the fans, the two on the case are 80mm and the one on the heatsink is 120mm. The arrows show direction from each fan.

Having discovered this, I turned around the fan on the back which currently leaves me running like this:


This didn't seem to make any real odds to the temp, but presumably is better.

I then thought about the design of the case, and wondered if the config below would be a better idea:



Do you think it would be a better idea to go with the latest proposal? This would work with the case design more closely (the top fan really just blows out cold air, even when CPU is hot at present)
The disadvantage would be that I would have a 80mm fan blowing into a 120mm fan from about 2-3 cm away and I don't know if this is a good idea really.

Additionally, would there be any value in putting a second 120mm fan on the other side of the heatsink? This would give me a kind of blow, suck thing going on (hrhr) but would this realistically offer any benefit?

[Clunk]

Fans generally blow towards the side that has the arms that hold the fan in place.

[DougMcDonald]

That's fine for heatsink fans, but what about case fans?

[Clunk]

Huh?

Edit: Look, this fan would be blowing towards you. It is generally the same for all fans.

[DougMcDonald]

Ah i see, misunderstood! Thought you were referring to the clips to attach fan to HS

Ok, so that leaves two questions,

#1 - Would i benefit do you think from reversing the back fan to blowing inwards, and having the cpu fan blowing in the same direction?

#2 - Would there be any advantage in putting a 120mm fan on either side of the heat sink?

[danroyle]

if you suck in your cold air from the back of your case that will not work so well for the following reasons

1,most people have there case close to a wall so there wont be much room for fresh cool air to get round the back
2,you will be pulling in air that will most likely be already warm as with a standard case your psu blows its warm air out the back and you will be recirculating it


generally it is best to intake air from the front and run it straight through and blow it out the back using a wind tunnel effect

[Clunk]

Best way is to try both ways, and also try all the fans blowing inwards, that worked best on my V1000.

It will also depend on how cluttered your case is with wires and other bits and bobs.

[DougMcDonald]

My PC has roughly equal room in front and behind, so I'm not sure that would make all that much difference.

Also the air from the PSU is colder than the ambient temp (currently!)

I just feel like the outlet on the top is not being used as effectively as possible. I also think the outlet on the back is being crippled by the fact its only an 80mm fan with no room for a 120mm

EDIT: Shutting down to try option three, lets see if it helps

[DougMcDonald]

Option three was a good few degrees higher so i reverted to option two.

Since the top outlet fan it unused in my opinion, i switch it to become and intake fan and i seem to have dropped 2 degrees.

Current config is same as option two, but with the top fan blowing inwards.

[DougMcDonald]

Temps looking good now (with side off admittedly)

Running 360x9 @ 30-31 idle and 50-52 after 2 hours on Orthos.

Will check again with side on and see the difference.

Have ordered a couple of sharkoons to replace the lian-li 120mm fans which are a couple of years old (v dirty etc) to see if that helps.

All my case fans are running at different speeds and I can't find anything which seems to tell me what they RPM they are actually using. Speedfan only detects the cpu fan. I've been using the asus in built tooly things but they seem to also miss one of the fans, and report a different CPU fan speed to speedfan.

Oh well!

[Blitzen]

You load temps are 20 degrees higher than idle???? Bloody hell thats a big difference.

You sure that these fans are blowing the correct way?

[DougMcDonald]

Certain on the fans now,

I always seem to get 20 degrees higher under load. It was the same previously.

Is this abnormal? What kind of temps are you getting?

[Clunk]

Is this abnormal? What kind of temps are you getting?

Nope, its normal, and the gap will be bigger, the longer its been on, and the higher the ambient temps are

[DougMcDonald]

Yeah I thought that might be a case, after half an hour or so on Orthos I was sitting at about 45-46, after 2 hours 52-53.

I am pleased that a matter of seconds after stopping orthos I'm back to 35 and a minute or two later back to 31-32. Suggests the cooling is fine after taken off load.