Suck or blow?

11-10-2014, 08:26

Apologies for the Daily Mail style subject!

Question - tower case with two fans - one at the back and one mounted on the top of the case. Which way should they be mounted?

My top fan is effectlvating sucking air out - when I hold a piece of paper over it, it blows away - if it was blowing air into the tower the paper would stick.

So which way should they be mounted?

BenMcr · 11-10-2014, 08:28

Depends where the other one is but I think having the top one as the extractor is correct.

http://www.tomshardware.co.uk/faq/id...uter-cool.html

Quote:

Rule #3: Exhaust Out the Top and Rear, Intake Through the Bottom and Front

One of the most important things to remember about cooling: heat rises. That said, it makes the most sense to place your exhausting fans near the top of the case while your intake fans stay near the bottom.

11-10-2014, 08:31

Intake and exhaust - I still prefer suck and blow!! :-)

OK - so rear intake (oh dear) and exhaust at the top - I think that's way they are configured so all good then.

raging bull · 11-10-2014, 08:40

Do you not have a fan/s on the front?
My tower case has twin 80mm fans sucking air in, then as yourself 2 others exhausting.

11-10-2014, 09:19

No - rear fan and top fan - oh and of course the CPU fan.

papa smurf · 11-10-2014, 10:41

i can't speak for your pc but i generally suck in at the top and blow out at the bottom

Jimmy-J · 11-10-2014, 11:19

I use 2 large front fans for sucking, whilst the rest do the blowing.

MovedGoalPosts · 11-10-2014, 11:27

Try and think about how air will move in the case. You aren't just cooling the CPU and even providing air to the GPU 's fan system, you need to move air over the motherboard and even your hard drives. Your PSU may also need air.

What are the points of entry to the case, even if they don't have fans. Are there vent grilles on the front and sides? If plenty of vents then your top and rear can probably both be exhaust as the air will get drawn in elsewhere. But if the front is effectively sealed then that rear fan should probably be an intake.

Some software can help you monitor temps on certain parts of your PC. That may help you find the best arrangement of fans, and their speeds.

Taf · 11-10-2014, 12:12

I saw a college experiment where different fan locations and directions could actually make "null" areas that caused overheating. And with modern hard drives, RAM, VRAm, etc. all preferring a cooler environment things could become very bad very quickly if the fan configuration was wrong.

Plus more air movement can equal more intake of airborne fluff and dust that could get trapped and thus cause overheating.

Most of the electronic equipment I used in the RAF had air filters, but I've never seen filters on PC's.

MovedGoalPosts · 11-10-2014, 12:22

You can get separate filters to mount with fans. http://www.overclockers.co.uk/produc...428&subid=2363

I've also had a coolermaster HAF 912 case that had front filters pre fitted, whilst many cases do at least have a fine mesh. Even so a periodic blowing out of the case inside can be a good thing.

alferret · 11-10-2014, 15:43

I have 1x120mm front & 1x120mm btm (both filtered) for intakes. 1x120mm top, 1x120mm rear 1x120mm side for venting.
Dependant on style of case is to whether its best you have positive or negative pressure within the case.

qasdfdsaq · 11-10-2014, 18:36

Both rear and top fans should be blowing air out. Cases are designed for air to flow from front to back. Heat rises, so secondary flow is from bottom to top.

11-10-2014, 19:50

Looks like I'm missing a few fans then. I'll have to get a couple of 120mm fans when I do the PC refresh .

qasdfdsaq · 11-10-2014, 23:43

You don't really need a huge number, again unless you're excessively overclocking, modern processors are reasonably efficient and low-power compared to yesteryear's, plus your power supply will already have a (likely) 120mm exhaust fan. Processors (non-overclocked) don't generate any more heat these days than they did ten years ago, when they built PCs with a single 80mm exhaust fan.

I've a friend who has a micro-ITX case, full-power Haswell CPU, and a GTX 780 card with just two 120mm exhaust fans, and it stays pretty cool and quiet. That said, if you're using air filters it's useful to have additional intake fans due to the pressure differential.

rhyds · 12-10-2014, 07:18

Quote:

Originally Posted by Taf

Most of the electronic equipment I used in the RAF had air filters, but I've never seen filters on PC's.

I think it's down to the sensitivity of the equipment to dust versus the amount of dust you expect to deal with. Aside from causing some cooling issues PCs don't mind dust, and the average home/office is usually reasonably dust free.

If however your dealing with high power radar/IT equipment that might be used in desert environments then filters are probably a necessity.