Do i need to fit a fan grill above my cpu cooler?

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mascott
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Do i need to fit a fan grill above my cpu cooler?

Post by mascott » Wed Jul 11, 2012 9:21 am

Hi
i bult my first pc back in january and the case i bought was the antec veris remote black, the cpu cooler i ended up buying for it was the GeminII SF524 to fit on a amd 960t be cpu but the total height of the cooler is 105mm and i have about 10mm clearance left to the top of my case with it fitted and was happy with how it peformed. have done a bit of reading on the web since then and read on a few forums that there should be about 25mm clearance above a fan for it to work proberly, so was thinking would i be better to cut a hole above my fan and fit a grill? or just leave it as it is as the temps i seem to get are not that hot i think, have attached a image to this post and if any one could advise me on if my temps are ok i would be most gratfull :-)

Image

lapon
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Re: Do i need to fit a fan grill above my cpu cooler?

Post by lapon » Mon Jul 16, 2012 6:04 am

I think a case hole and a grill would be the best fix for the lowest cost. Fans really do need a larger space than about 1cm to pull air from. I haven't done the modeling, but I would bet the clearance should be roughly half the fan width; SPCR'ers please correct me if I'm wrong. I would probably recommend a shorter cooler if you can spare the money, the Scythe Big Shuriken 2 Rev.B just got a pretty good review from here, though the 960t is a hot CPU.

Check out this link about how grills affect fan noise and performance. They were testing the grills right next to the fan, but it might help to pick a good one since the case side is close anyways. Alternatively, can you just run with the case open? If the CPU/PSU/GPU fans are relatively quiet its not a bad temporary fix and you don't need to have the case fans on anymore since the case is wide open.

ces
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Re: Do i need to fit a fan grill above my cpu cooler?

Post by ces » Mon Jul 16, 2012 8:43 am


ces
Posts: 3395
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Re: Do i need to fit a fan grill above my cpu cooler?

Post by ces » Mon Jul 16, 2012 8:51 am

lapon wrote:but I would bet the clearance should be roughly half the fan width
I was informed by a fan expert that it should be one fan blade width. That sort of made intuitive sense to me.

That is roughly 25mm. Actually a bit less if you think about it.

If you look at the top fan on the Noctua NH-L12 it is less, perhaps closer to 15mm. And if you run it with just the underfan, maybe it is 0 MM... or just in case 10mm - not for improved cooling - but to avoid noise generated by air turbulence through the longer path the air must otherwise travel through the fins. My guess is that the longer path might even improve cooling performance... bu at the cost of increased noise.

ces
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Re: Do i need to fit a fan grill above my cpu cooler?

Post by ces » Mon Jul 16, 2012 9:06 am

Two underfan Coolers that might be of interest, both of which can be expected to provide more cooling with less noise... and do so with overhead clearance.

Noctua NH-L12
 Actual Height with one bottom fan = 66mm
 Effective Height with one bottom fan (no extra breathing space required) = 66mm
 Actual Height with two fans = 93mm
 Effective Height with two fans (25mm extra breathing space required) = 118mm (actually you might be able to run it with 15mm of breathing room because the top fans blades are substantially less deep than the assumed 25mm)

Noctua NH-C14 (this one is a bruiser and should be able to cool almost any modern non-overclocked CPU with just one fan... and with plenty of cooling capacity to spare)
 Actual Height with one bottom fan = 105mm
 Effective Height with one bottom fan (no extra breathing space required) = 105mm

You will likely get the best cooling with the NH-C14, with a single underfan. I would use a 120mm Nexus for the underfan

The NH-L12 looks like it could live quite comfortably with both fans within the 115mm clearance you have without the need to cut anything. What is nice with two fans is that if one fails... no problem. The other one with prevent any melt down.

Taking a Deep Breath of Cool Air

If you want to cut, you could substantially increase the performance of either of these, you can both install one of them and cut a hole. If you do that you will pick up, up to an extra 10-15C of cooling just by going outside the case for ambient air.

Cutting a hole with the Noctua NH-C14, it would stick outside the hole by about 10mm and be able to get a good breath of the cool air. You could mount a grill on top of the fan itself. You could run it dead silent with two 120mm Nexus fans at 500rpm... and it would probably even handle a highly overclocked CPU with all the cool air and all that finnage.
Last edited by ces on Mon Jul 16, 2012 9:21 am, edited 2 times in total.

ces
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Re: Do i need to fit a fan grill above my cpu cooler?

Post by ces » Mon Jul 16, 2012 9:08 am

mascott wrote: have attached a image to this post and if any one could advise me on if my temps are ok i would be most gratfull :-) Image
For some reason the image is not showing.

mascott
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Joined: Wed Feb 01, 2012 1:41 pm

Re: Do i need to fit a fan grill above my cpu cooler?

Post by mascott » Mon Jul 16, 2012 10:11 am

Thanks for all the replys guys, i ran my computer with prime 95 and the image i tryed to show you were my temps after it had run for 3 hours which were 21c at idle and 37c at 100% load..this are the core temps.........when i was looking for a cpu cooler at xmas last year the noctua NH-L12 was not released thats why i ended up getting the coolermaster GeminII SF524 as i made the mistake of buying the corsair vengence memory with the high heatsinks and i could not find a cpu cooler that would fit with that memory :-( ..............think now that i will try looking into cutting a hole and fitting a fan grill just so that the cooler is getting a fresh surpply air from outside of the case :-)

ces
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Re: Do i need to fit a fan grill above my cpu cooler?

Post by ces » Mon Jul 16, 2012 11:06 am

mascott wrote:thats why i ended up getting the coolermaster GeminII SF524
I would also get a Nexus fan and replace the stock fan with it. Your temps look pretty good as is, but the Nexus should be quieter.

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