Norco 4224 120mm fan orientation

I'm building yet another 22 Drive Beast for a client.  I'm using the Norco 4224 case, the 3 x 120mm fanplate, and three of the Scythe SY1225SL12H 120mm "Slipstream" Case Fans.  I chose those fans as they offered a good balance between low dBA ratings (with the case closed they are very quiet!), high CFM ratings, and reasonable cost ($32.76 for all three).

All of this is pretty much standard operating procedure.  I also always install the fans on the side of the fan plate closer to the mobo and further from the drives, as it offers much more space to hook up the power and miniSAS cables to the drive backplanes.  I also have the rear stock 80mm fans installed but unpowered at this point (the client asked that I leave the stock rear fans installed instead of removing or replacing them).

However, I made a mistake - I installed the 120mm fans backwards.  The case's stock 80mm fans pull air from the drive bays and push it out the back of the case (carrying the hot air from the cpu/mobo/cards with it).  Normally I install the 120mm fans in the same orientation.  This time I accidentally installed the fans the other way around, so that they pull air from the mobo/cpu part of the case and push it through the drive bays out the front of the case.  Of course I realized this after routing all the cables through the fanplate, etc....

After a few expletives, I realized that maybe this wasn't such a bad thing.  In general, we worry about our hard drive temps more than the temp of the CPU or cards.  With the fans blowing air directly across the hard drives, it seems to me that they would actually be getting better cooling.  The counterpoint is that the fans would also be pulling warmer air from the CPU/mobo compartment and blowing it across the drives.

My brief testing with this theory resulting in somewhat uninspiring results.  When the case top is open, the air hits the backplanes and turns upwards, so it does little to cool the drives.  With the case top closed, I can actually feel some air being pushed out through the vents in the front of the drive bays, but not as much as I would expect to feel...there seems to be significant resistance from the drives and drive bays, so I'm a bit worried that most of the air is just bouncing off the backplanes and circling in the space between the fan plate and the drive bays.

I also took a look at the drive temps during a preclear (writing phase).  I only have 6 drives to test with right now (5 Hitachi CoolSpins and 1 WD EARS).  All drives stayed in the optimal range for the duration of the preclear cycle - between 30 and 40 C, generally towards the lower end of that.  For comparison, the drive temps are exactly the same during the same preclear cycles in previous 22 Drive Beasts that I've built....so based on that test it doesn't matter which way the fans are blowing.

I wish I had many 7200 rpm drives to test this fan orientation further, but alas I do not.  Is anyone else running a Norco case with their fans blowing back to front?

I also always install the fans on the side of the fan plate closer to the mobo and further from the drives, as it offers much more space to hook up the power and miniSAS cables to the drive backplanes.

Not entirely to do with your topic, but all I can say is: BRILLIANT!! Is this standard procedure that everybody follows when swapping out the fanwall? Am I just a drone, toeing The Great Norco Line ?  When I put my 120mm fanwall in, I installed the 120mm fans the same way the 80mm fans were installed: On the side with the backplanes.... The end result of course is virtually no space to get your hands in to work, and almost no clearance between the SAS cables and the fan blades...

Why I never considered putting them on the other side is beyond me... Stuck too much 'in the box' I guess  . In my humble defense, I have no actual issues with the way it is, just inconveniences. Looks like I have some rearranging to do tonight .

Oh, and to be on topic: My fans are sucking air over the drives, same way it came. Logically I believe pulling cooler outside air over the drives will end up providing  better cooling then blowing warmed air (from cpu etc), past the backplanes, and out the front. I wouldn't be surprised if the temps do actually rise, once you get enough drives in the bays...

I think once more drives get in there you will run into the problem of there being no "easy" place for the air to go.  Pulling to (hopefully) cooler air from the outside and over the drives is probably the better approach.

I also always install the fans on the side of the fan plate closer to the mobo and further from the drives, as it offers much more space to hook up the power and miniSAS cables to the drive backplanes.

 

Not entirely to do with your topic, but all I can say is: BRILLIANT!! When I put my 120mm fanwall in, I installed the 120mm fans the same way the 80mm fans were installed: On the side with the backplanes.... The end result of course is virtually no space to get your hands in to work, and almost no clearance between the SAS cables and the fan blades...

 

Why I never considered putting them on the other side is beyond me... Stuck too much 'in the box' I guess  . In my humble defense, I have no actual issues with the way it is, just inconveniences. Looks like I have some rearranging to do tonight .

Comically, I believe I first stumbled upon that method by accidental means as well on one of my first 4220 builds.  I installed the fans on the mobo side of the fan plate, installed the fan plate, then later realized that I had them on the side opposite of the stock fans.  However, it didn't take a forum discussion for me to figure out that the arrangement was better

A few apt quotes...

One of the advantages of being disorderly is that one is constantly making exciting discoveries.

- A. A. Milne (1882 - 1956)

The more original a discovery, the more obvious it seems afterwards.

- Arthur Koestler (1905 - 1983)

source

I think I might have to post that first one on the wall of my server workshop

On a serious note, if your server is already working I don't see much of an incentive for you to dismantle it to move the fans around....

I think once more drives get in there you will run into the problem of there being no "easy" place for the air to go.  Pulling to (hopefully) cooler air from the outside and over the drives is probably the better approach.

 

I have to agree with Prostuff1 on this. Having worked on the 5x3 cages and then some pretty large server and storage arrays, I would think as you populated drive bays, you would generate more resistance. Depending on how the drives were layed in your build, air could have been flowing through an empty drive slot next to it, helping to keep it cool. Fill it all up, and this becomes a problem, with more resistance. Plus you have all that air being deflected and redirected by all the cables.

Cooler air brought in from outside versus somewhat warmed air from the interior to cool the drives...

Maybe I am just to caught up in the years of "push" and "pull" designs to see that it could work.  Maybe, if there is enough openings on the backplane...

Shawn