I had previously asked about whether it was necessary to augment the stock fans on my HAF 912 and the consensus was that I would probably be fine if I'm not overclocking. However, Newegg just sent me a 25% case fans coupon which I would like to take advantage of the offer since I will probably do some overclocking in the future.
I've currently got a stock 120mm intake in front and a stock 120mm exhaust in back. Both are fairly low CFM, though I don't have an exact number. I can put two 120mm's on the front or one 200m; one 120mm on the back; two 120mm's or one 200m on the top; and one 120mm or one 140mm on the side. I don't have my motherboard (I'm picking it up Wednesday) so I'm not sure as to the positioning of the side fan yet.
(1) Which setup would you recommend? Is there a better configuration that I haven't considered?
(2) Are my fan choices good?
(3) Is it better to go with fixed speed or variable speed fans? The variable speeds seem to have a much higher CFM at their max and are a bit quieter at their lowest speed. They are pretty loud at their max though.
(4) 200mm or two 120mm for my front intake? Adding two of 120mm variable speeds would have a higher max CFM but the 200mm would have a higher CFM than the two fixed speed 120mm's.
Here's my build:
CPU: Intel i5 2500k
Motherboard: Gigabyte GA-Z68XP-UD3 LGA 1155 Z68 ATX
Memory: G.SKILL Ripjaws X Series 8GB
Video Card: Gigiabyte Ultra Durable VGA Series GV-R685OC-1GD Radeon HD 6850
Case: HAF 912
HD 500GB 7200 RPM 16MB Cache SATA 6.0Gb/s
Power: Corsair Builder Series 600 Watt ATX 12V Power Supply
Optical Drive: ASUS 24X DVD Burner
Operating System: Windows 7 Home Premium 64-bit
CPU Fan: COOLER MASTER Hyper 212 EVO
sounds to me like you should get a 200mm for the front and top, and I believe you have a spot on the bottom to put your current front fan in. If you have the money go for a 140 for the side as well, but that is likely overkill. Aim into the case from the front bottom and side, and out of the case through the back and top. Always have more air blowing in than being exhausted to cut down on dust accumulation. Low RPM and low CFM is fine when you have that much space to work with, what matters is a constant flow of fresh air, and that it moves in one direction instead of being recirculated throughout the case.
According to the specs listed you wont be producing enough heat to worry about overheating even with the stock fans in the case. Only get the extra fans if you intend to run all of them slower to reduce noise, otherwise it is pointless.
In my opinion, case cooling is largely over-rated. As long as you have some fans spinning, the turnover of airflow entering and leaving the case is generally fine.
Swapping out all your fans for higher CFM ones, is likely to make either no difference at all, or a difference of just a couple of degree's. The only fans I really rate as "worthwhile" are side fans that can blow cool air directly onto your heavily OC'd GPU or SLI configuration.
A single 200mm fan will provide more cooling than x2 120mm fans, they will also run much quieter so if anything, stick with 200mm fans where possible.
More importantly, DUST FILTERS. It's no good blowing huge amounts of air in and out of your case, if you don't have dust filters because your case is just going to get clogged up more quickly having a negative effect. Get dust filter mesh for ALL intake fans and you should fine your system stays almost completely dust free inside.
Luckily my front intake comes with a fairly decent filter.
Based on everyone's comments, I'm leaning either towards doing nothing or putting the 200mm on the front and moving the 120mm to the top as an additional exhaust. I've been reading through reviews for the HAF 912 though and many recommend adding additional fans as the stock airflow is lackluster. But some of their testing systems are more high-end than mine.
One more question: in the stock configuration, once I add my PSU as an exhaust, won't I have negative pressure?