Airflow Questions

[surfsatwerk]

I know the Sonata is not an ideal case for cooling by any stretch of the imagination but my desk is in my family's living room and part of the bargain I made with my wife when I upgraded was to ditch my old Chieftec, which was cherry with a blowhole and everything, for something a little less loud and obnoxious.

Now, of course, I'm running into temp issues and I just wanted to shoot some ideas out there and double check that my thinking is reasonably sound. The way the case is setup is there are 2 120mm fans in the case with the outlet is positioned where you typically expect it to be on the back of the case under the PSU. But I had to position the intake fan inside the HDD cage because my 9800 GTX was too large and wouldn't fit inside the case with the fan in the normal position on the motherboard side of the HDD cage.

Inside that cage about 1/3 of the fan's surface area is blocked by the cage itself. I can feel very little air movement from the intake fan and I can feel a significant amount of air coming in through the cracks around my various drives outside the front of my case.

Trying to make the best of a bad situation my thoughts were to reverse the direction of my fans so that the back of the case would be pulling air directly into the case and mount the fan for the Ultima 90 on the side closest to the back of the case. This way it's pulling air directly from the intake onto the Ultima 90. Then all the hotair will be flowing out the front of the case. Does this seem like a reasonable solution or is there some basic physics here that I completely overlooked?

 

[panfist]

This is usually a very bad idea unless you have excellent exhaust on the front or side of the case. Yes, your CPU temps will appear cool initially, but you're blowing the exhaust from the CPU all over the inside of your case. Your case temps will go way up, and it might not be apparent until 1 hour or more at load.

Secondly, there would be no reason to mount the fan on the back side of the ultima 90. Your new intake fan would be blowing air right onto the ultima 90 already, so having it mounted frontside blowing toward the front would be better. If you mount the chassis fan and the CPU fan too close to each other they will just be "competing" with each other.

I would only reverse the airflow if you're willing to install a 5.25"-mounted exhaust fan in the front. But you'd only accomplish this by ripping the front case door off. Which I always do anyway...those things are annoying...but hey, you might like it.

Alternatively you could invest in a smaller fan which you could mount under the 9800GTX.

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Lastly...define "temp issues." How high are your case, CPU and GPU temps? My final words to you are that reversing your airflow is definitely NOT a magic solution. You could try it, it might work, but I doubt it. You'd be better off identifying exactly where your temp problems are and targeting a solution right there.


edit: also, are you using C1E enhanced halt state? How about EIST? These options will cut down on your heat and your power bill.

 

[panfist]

delete this, i quoted when i meant to edit.

 

[Zepper]

Yup, the idea of putting the fan on the rear of the HDD rack came up with the first Sonata when quiet 120mm fans weren't all that available or cheap mainly to put the fan a bit farther away from the user's ear and thus lower the apparent noise. Unfortunately they never ashcanned that idea for the later two versions when cheap, low-noise, 120mm fans are all over the place and video cards became absurdly long... In hindsight, it wasn't all that good an idea in the first place as air blockage from the cage makes life difficult for any front fan in the std. location.
. Anyway, if it was mine (actually it wouldn't be because I would have purchased a Rosewill R5605 instead ), I'd cut a sizable vent into the bottom of the case at the base of the HDD rack (the farther forward and lower the better - don't forget to treat the cut edge to some paint right away to prevent rusting - and make sure you got all the metal filings/shavings out with vacuum and tack cloth). I'd put some pieces of sticky-back Velcro hook material around this new vent hole (probably on the outside of the bottom) and stick an adequate piece of air conditioner foam filter over the new vent opening to help keep dust and critters out - I usually cut each 1" square of Velcro hooks into three strips for this purpose. Then obtain a higher air flow, while still low-noise (perhaps a Scythe Ultra Kaze) rear fan to pull air in thru the new vent. Then I'd try to sneak one of those new, low-profile fans in between the front panel and the HDD cage just to get a little breeze going over your HDDs. That's what I'd do - now put your thinking cap on and decide what you will do.

.bh.

 

[surfsatwerk]

Thank you both for your input. I tend to become rather infatuated with my own brainstorms so I missed the problems you pointed out with the setup I described. My case ambient temps are rather high when my system is idle, around 10C or more higher than the temp outside my case. And as a result my core temp readings are around 45 to 50C under minimal workload. My max core temps under OCCT and Orthos for my cpu are never more than 65C, which to my understanding is safe but far from ideal for my particular chip.

Originally posted by: Panfist

Secondly, there would be no reason to mount the fan on the back side of the ultima 90. Your new intake fan would be blowing air right onto the ultima 90 already, so having it mounted frontside blowing toward the front would be better. If you mount the chassis fan and the CPU fan too close to each other they will just be "competing" with each other.

I'll definitely take your advice on that. I'll make sure to run my system at load for a couple hours to make sure that my ambients are stable under load and don't creep up because there isn't enough air exiting the case.

I do have a decent dremel kit that I've used for various mods in the past, but I hadn't ever thought of cutting a hole in the bottom of my case instead of the top. Thanks for the idea Zepper if I can't reach a satisfactory temp situation I'll definitely attempt some modification along those lines.

 

[Zepper]

I'd also block off the vent holes above the PCI slot openings because if there is any restriction for air for the rear fan, then air will be pulled in thru there and go right out the rear fan w/o having done any cooling work. You want your main cooling path as long and reasonably leisurely as possible so the air picks up a good amount of heat along the way to carry out of the case - don't want any airflow shortcuts... The average temps might be a bit higher, but the overall cooling will be more efficient.

.bh.

 

[panfist]

If you have an e8400, or any other penryn for that matter, I wouldn't trust the temperature readings from any program. At least not in terms of absolutes. It's good for learning relatively how much your temps go up at load compared to idle, but that's it; you won't get a good absolute reading from any program. You can't trust the readings from coretemp, realtemp, speedfan, everest, or any other program. The only way you can trust these readings is if you calibrate them yourself.

I have an e8400 that my motherboard and everest tells me idles at 50C and loads at about 63C, but that is completely impossible. Even after leaving it at 100% load overnight, everest reports 63C, but the base of my heatsink (a thermaltake sonic tower, basically a tuniq tower clone) feels completely cool, like barely above ambient. I can put my finger on the base of my heatsink literally about 1 CM away from the chip itself and it feels COOL. If I remove the fan, it reports a load temp of 70C and at this point it's beginning to feel warm. My motherboard reports my northbridge temp at 45C and that feels waaay hotter than my CPU heatsink.

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If you don't have a penryn, yeah those temps are a little high but definitely within the safe zone. If I were you I wouldn't worry too much about it.

Also, if you're on stock cooling, consider spending $30-$40 on a CPU cooler. Considering that any project where you take a dremel to your case is going to suck up at least a few hours, you have to ask yourself how much is your time worth.

 

[surfsatwerk]

I ran my system for a couple hours overclocked at load and got at around 10C better temps with both fans blowing air into the case and the fan on my Ultima 90 in pull configuration. Yeah it feels like a dumb setup but I'm going to try a few other different things when I have the time but anything that gives me a bit more headroom for my overclock is cool beans. I have an E8400 like you Panfist and I agree with your experience regarding temps with this chip. I've had coretemp telling me it's 70C but I touch the base of the Heatsink and it feels no warmer than ambient.