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Need help with Airflow *pic*-updated

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March 20, 2009 5:21:46 AM

Just built new rig and would love some input on optimal airflow. My system runs pretty cool except for the 2x Crossfire 4870 1gb cards..... They run a bit hot, so ideally anything to optimize cool air in there to get temps better.

The case is a cooler master 690.
Pretty sure I have 7x 120mm fans up in there.

I know my cabling sucks, have not had time to get to it.(could this possibly be cause for high temps on video cards ?

red arrows: airflow out - blue arrows: airflow in - purple arrows: power supply airflow direction
green arrow: cpu fan direction
Blue Circle = fan on side of case blowing into the case.




System Specs:
CPU: Intel Q9550 2.83 Core 2 Quad
MB: GIGABYTE GA-EP45-UD3P
GPU: 2x Crossfire Sapphire 4870s 1gb
Ram: G.SKILL PI Black 4GB(2x2gb) DDR2 800
HD: Western Digital Caviar Black 640gb 32mb cache
DVD: SAMSUNG 22X DVD±R DVD Burner SHS223
PSU: CORSAIR CMPSU-850TX
CPU Cooler:XIGMATEK Dark Knight
Case: Cooler Master 690
OS: Vista Ultimate 64bit
7x 120mm fans

More about : airflow pic updated

March 20, 2009 9:43:42 AM

Having the heatsink face the bakc of the case and not the top would help, but the rest seems fine to me. You could try not using the side fan and you might get better performance because side fans generally just impede airflow.
Related resources
a b ) Power supply
March 20, 2009 10:12:20 AM

Sorting the cabling will help no end!
March 20, 2009 10:18:21 AM

I read that cable management can enhance cooling by 1~3 C but there is no hard proof. To think of it, the mess I see in your pic is definitely impeding air flow. You should try rerouting your cables to make clear road for air, you'll lose nothing (other than your time) and it'll improve the interior's look.
What temps you've got on the 4870s? Those beasts are known to run hot especially on the reference cooler.
March 20, 2009 10:31:42 AM

Examine the temps of your GPUs with the side fan on and off..See for yourself which way is better.
Personally I believe you'll get the best results if you disable one or both of the front intake fans (YES i said DISABLE) and seal their openings. That way the 3 exhaust fans (red arrows) will force all the fresh air to enter the case through the opening of the side fan (whether turned on or off), thus the fresh air will cool your GFX cards first. It may increase the temps of other components (by few degrees, thus not exceeding their thermal specification) but your GPUs will definitely be cooler.
My best advice: you'll achieve the best results by trial and error, and long hours of testing (playing crysis for example and watching the temps of all components by Rivatuner's monitor), this is how I came up with my cooling plan 1 year ago, it took me about a month!! :p 
March 20, 2009 10:38:51 AM

I just noticed your 4870s have custom coolers. The efficiency of those is unknown for me. If you don't intend to invest in 3rd party coolers, you can always increase the fan speed by Catalyst's overdrive, ATI tools or rivatuner, on expense of more noise.
a c 144 ) Power supply
March 20, 2009 11:12:32 AM

The_Blood_Raven said:
Having the heatsink face the bakc of the case and not the top would help, but the rest seems fine to me. You could try not using the side fan and you might get better performance because side fans generally just impede airflow.

I don't know. I have an Antec 900 case with the CPU heatsink oriented vertically. I figure warm air wants to rise. Why fight physics. But it does look like some cable management will go a long way.
March 20, 2009 12:25:16 PM

4870s run hot anyway. You can use a 3rd party tool to increase the fan speed of the 4870 cards.

I agree about the cable management. That is a definitely MUST. Zip-ties are virtual miracle workers when it comes to cable management.

Your airflow chart is helpful. I would shoot for some negative airflow, meaning more air going out than coming in. That way cool air is coming in through the cracks vs hot air being dispelled from the cracks. It ensures that most of the air in the case is cool and isn't recycled hot-air.
a c 248 ) Power supply
March 20, 2009 4:49:49 PM

I see another problem. Airflow from the fan at the bottom front of the case is severely restricted. The hard drive cage and hard drives are blocking air. In fact, I am willing to bet with the sideway configuration that the hard drive cage and hard drives are blocking at least 80% of the air flow. Then you've got a tangle of cables behind the hard drive cage. Try and organize the cables to reduce blockage. In addition, if the fan at the bottom front has an air filter or interior grill you can safely remove them. That should help get a little more air to the video cards.

March 20, 2009 9:41:51 PM

So I did a little cable management.

I changed one of the fans the top front intake I moved to the bottom of the case so that it is blowing cool air from the bottom straight up.

heres some pics of the end result. I think I reduced my temps inside my case by a few degrees.

Im still stuck with whether this is optimal air flow or not.






Motherboard 43 °C (109 °F)
CPU 27 °C (81 °F)
CPU #1 / Core #1 36 °C (97 °F)
CPU #1 / Core #2 33 °C (91 °F)
CPU #1 / Core #3 38 °C (100 °F)
CPU #1 / Core #4 38 °C (100 °F)
GPU1: GPU Diode (DispIO) 51 °C (124 °F)
GPU1: GPU Diode (MemIO) 56 °C (133 °F)
GPU1: GPU Diode (Shader) 56 °C (133 °F)
GPU2: GPU Diode (DispIO) 52 °C (126 °F)
GPU2: GPU Diode (MemIO) 57 °C (135 °F)
GPU2: GPU Diode (Shader) 52 °C (126 °F)
March 20, 2009 9:48:20 PM

jsc said:
I don't know. I have an Antec 900 case with the CPU heatsink oriented vertically. I figure warm air wants to rise. Why fight physics. But it does look like some cable management will go a long way.


Not sure why I got marked down 1, but what I said was true. A heatsink mounted pointing towards the back is generally better than one pointing up, because of the physics of the fins. Heat can be drawn from the side of the fins better, because the fines will be longer in this scenario. Also a heatsink like that will also block airflow going to the top. As I mentioned before, this is only a minor thing that is more nitpicking than anything.
March 20, 2009 10:16:55 PM

boudy said:
You could put a PCI slot fan in between the 2 4870s. or maybe 2 PCI slot fans after both the 4870s?

http://www.newegg.com/Product/ProductList.aspx?Submit=E...

They are relatively cheap so its not like you are giving up an arm and a leg for some decent cooling.


Yes, I use a slot fan and find its a good/cheap way to expel heat from video cards. It can be installed in any expansion slot you have a hole for in the back; doesn't actually need an expansion 'slot' to plug in to, just a slot out the backside of the case...
March 20, 2009 10:43:34 PM

doormatderek said:
Yes, I use a slot fan and find its a good/cheap way to expel heat from video cards. It can be installed in any expansion slot you have a hole for in the back; doesn't actually need an expansion 'slot' to plug in to, just a slot out the backside of the case...



Its hard to see, but both of these gpu's have blowers blowing in the back.
March 20, 2009 11:08:46 PM

well.. what are their fan speeds? Do you adjust the speeds while gaming or have them speed up automatically? You could potentially install a slot fan above the both of them, exhausting heat...
March 21, 2009 7:59:25 AM

I think the temps posted above are in idle state. If so they are normal, but if they were taken under full load (prime 95+ loops of crysis bench for example) they are terrific -for air cooling-, and you need not worry.
PCI slot fans tend to be noisy and their cooling efficiency does not go in parallel with their noise.
Try disabling the front fans as I mentioned previously and see the results.
March 21, 2009 8:12:05 AM

Just add a spot cooling fan between the 2 cards or facing at those 2 cards hang a fan inside the case it's not pretty but it allows for the air to move properly between the two cards.

Adding a spot cooling fan loosly tied and then later screwed inside of my case really helped lower my gpu temperature about by 5c

I doubt you really need 7 fans i have variable fans and just use asus quiet fan system to make my fans spin at about 1100 rpm but they can move right up to about 2400 for each of my 4 fans and 2700 for my cpu fan (i rather never have it at full load it's like a freaking windstorm comming from my case)
March 21, 2009 3:30:31 PM

IzzyCraft said:
I doubt you really need 7 fans i have variable fans and just use asus quiet fan system to make my fans spin at about 1100 rpm but they can move right up to about 2400 for each of my 4 fans and 2700 for my cpu fan (i rather never have it at full load it's like a freaking windstorm comming from my case)



well for 7 fans in the computer you would think this thing winds like an F-18; It does NOT though. The 120mm in here are super quiet. Do I need them ? No clue, still waiting for someone to chime in about the air flow design and fan placement.

The fan speeds from my original post was my GPU fan speeds at 60%. I forgot to change them from boot up. I found a comfortable speed while not gaming to be 31% (1300rpm). This adds about 5 degrees more heat to my gpus. Which still puts fixing the cable managment to decreasing my temps by 5 degrees.



@rock1987: That thread was a "Show off your computer thread" didn't have anything to do with cable management. pasted wrong link maybe ? :) 

@the_Blood_raven: in regards to the cpu heatsink preventing airflow, I would have to disagree with you there. The fan itself is pulling air straight up thus actually increasing airflow.
March 21, 2009 10:52:42 PM

@ ScottX "No clue, still waiting for someone to chime in about the air flow design and fan placement. "
One year ago I read many case studies supporting the directional air flow, i.e multiple directions of air will cause turbulence and decrease the overall renewal of air and also increases noise slightly, while having the intake an exhause fans blowing the air in one direction yields significantly better performance per noise . I tried that and it worked perfectly for me.
You do remember that hot air rises up naturally (Physics lesson no 1), so the direction of air is preferrably from down upwards. So I suggest the following:
1. Mount an intake 120 mm fan at the buttom (after you manage your cables properly of course, they are still messy!)
2.DISABLE both front intake fans, the side intake fan (the lower one) and the rear exhaust fan and UNINSTALL them.
3.Seal the holes of both front fans, rear fan and the UPPER (not the lower) fan hole of the side panel (by a transparent tape for example) .BTW the HDD don't need special cooling, see the survey of google servers HDD and know that most HD nowadays can operate at 65 deg C.
4.Keep the 2 upper exhaust fans, keep your CPU cooler blowing upwards and keep the PSU as it is.
By this you'll achieve a non-turbulent, physics-aided single directional air flow with the minimum number of fans, noise and -if it matters to you - power consumption. Having 1 intake fan and 2 exhause will achieve negative pressure inside your case and the air will have to be sucked in though the hole of the lower fan hole of your side panel , thus cooling the graphics card. That's why I told you to seal the upper and not the lower hole.
About a year ago I did a similar plan on my case (through mods) and I used paper tissues to confirm the direction and magnitude of the air flow at each hole in my case. Every thing still works nice even in my country's extremely hot summer and with my E6750 overcklocked from 2.66 to 3.66 @ 1.45v.
March 22, 2009 4:38:01 AM

avatar_raq said:

1. Mount an intake 120 mm fan at the buttom (after you manage your cables properly of course, they are still messy!)



The latest picture I posted is still messy ? I have complete unobstructed airflow inside my case.... All my wires are on the back side of the cage... the 3rd picture i posted shows how they are all fitted in the back which is where almost every cable management tutorial has advised me to place them.

If you could be a little more specific (non nit pickingly) it would be greatly appreciated.


also: your advice is to only have ONE intake fan brining in cool air ? well I can try it pretty easy and will report the findings. If you will note I had already placed a fan at the bottom of the case blowing upwards which reduced the heat by 5degrees.

Either way thank you for your reply and effort in assisting me.
March 22, 2009 9:45:41 AM

@Scottx:
"I have complete unobstructed airflow inside my case"
:ouch: I'm sorry, that wasn't obvious in the picture, it's one dimensional and it was hard to tell whether the cables are in front, just above or behind the buttom fan.
As I told you I always prefer the "out-take" fans to be more than the intake ones by one, to achieve -ve pressure, and I always seal the whole case and leave one hole for the air to be passively sucked in, usually near the hottest part of my system, the GPUs.
March 22, 2009 1:17:16 PM

@Scottx,
Sorry, I meant to have a look at these pics within the thread for cable management in cm-690



You can make use of all the holes in the CM-690 to route the cables and remember zip ties are your friends ;) 
Btw I also have a 4870 and what I do when not performing graphics intensive tasks is underclock the GPU & memory clock of the card and manually adjust the fan speed to 30~40% via catalyst control center. This not only saves power but also enables the card to idle at about 50~56c.
March 22, 2009 2:32:05 PM

1 thing I have learned from ATI, the machine that puts thermal paste on the cores is freaking useless. Get some good thermal paste (Arctic Silver 5, Arctic Cooling MX-2[my favorite], OCZ Freeze, or Tuniq TX-2) and replace the thermal paste by putting a drop of it the size of frozen pea where the old stuff was after you wipe it off with 70-99% rubbing alcohol.

Or you could just be happy because in all honesty your temps are fine and are actually pretty good GPU wise, though I recommend re-seating the CPU heatsink, it should be doing better than that. I usually fill the cracks on the base with thermal paste and make sure it is totally level with the pipes and press it in, or compact it in, and then put 2 small lines of thermal paste on the aluminum parts of the base (about half 3/4 of an inch long and as thin as possible). Put it on and twist it a little bit and clamp it down.
!