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Improving case airflow...

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January 28, 2010 11:54:58 AM

I'm looking to further improve the cooling in my latest build.

Current CPU temps: idle 28-30C, full load 51C
ambient ~70*F
the system is totally silent at max fan RPM, I could certainly stand some noise, maybe 10-15db increase if needed

I have been against putting a fan in front due to reports that it can be more of an obstruction than a help. I think improving the flow through and exhausting of hot air is a better idea.

I realize the positioning of my CPU cooler may not be optimal, but unless someone here wants to trade or buy my Xiggy hdt-s1283 and I stick on a CoolerMaster Hyper 212+, I'd prefer to just leave it as is. Maybe upgrade the fan (stock ~1500RPM, 56CFM) or change the TIM (currently using Dynex).

I also applied black duct tape over the vent holes in the left side of the case to improve airflow suction from the front to back.

I will be adding a HD 57xx-series GPU soon. The machine is also overclocked.






More about : improving case airflow

a b ) Power supply
January 28, 2010 3:17:00 PM

I would re-think your aversion to a front intake fan, especially with your planned new vid card.

Right now air from the lower section of the case (over the PCI slots) gets moved by two competing fan systems. One is the rear exhaust fan. The other takes air from over the PCI slots and runs it through the CPU heatsink; then the PSU fan sucks it in and routes it over its components and out its rear exhaust port. Of the two vent grille areas on the left case cover, the upper round one appears to be directly above the heatsink, so air flow in through it must turn down to get to the intake side of the CPU fan and then reverse direction, or turn up and bypass the CPU entirely to get to the PSU intake. Air that enters the lower rectangular grill goes directly into the PCI slot area where it is joined by air entering from the front intake grille and passing over the hard drive. I suggest these latter two combined shold be the main air supply route. But you say you used duct tape to block off some (both?) of the left cover grilles and force more air flow to enter from the front.

Now, add in the planned vid card with its cooling requirements. It may have its own fan system that draws air in from the bottom area of the case and exhausts it out its own rear vent. This would rob a lot of the air supply to the CPU and PSU path, as well as being simply a barrier to flow from the case bottom to the CPU intake area.

I would suggest that you want both of the left panel vents open to increase air availability to the PCI slot area and CPU fan intake area. But I also think that you should enhance that air supply even further by mounting a front INTAKE fan that blows air over the hard drive. In fact, a whole lot of this air stream will enter a little further up the case than right over the hard drive, approximately into the area of the end of your new vid card and the gap between that card and the CPU fan intake. That would restore air supply to the CPU cooling fan that otherwise will be blocked off by the new vid card itself.
January 28, 2010 3:53:26 PM

- maybe I'll unblock the vents above the PCI area to provide more direct outside air for when the discrete GPU gets installed

- the round CPU case side vent, when open looks in on the top of the tower cooler and is essentially half-blocked by the cooler with less than 1/2" of clearance between the actual panel and the top of the cooler - very close. As such, I may just keep it closed off since it doesn't seem to be a really prudent port of entry for air.

- I'm thinking of maybe putting a more powerful 120mm exhaust fan in and moving the lower powered "stock" Rosewill case fan to the intake position and see how this works.

- due to the inevitable barrier that a discrete GPU is going to create to the intake of the Xiggy CPU cooler fan, it may be more wise for me to unload this cooler in the classifieds and get the Cooler Master Hyper 212+ so I can make this "more right" by having a CPU that fan blows right through the heat sink and into the exhaust fan

if upgrading Intake/Exhaust/CPU fans, where is a higher CFM fan most effective?

Thanks for your input! It's really got me thinking more about how to make this system operate at its best!
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a b ) Power supply
January 28, 2010 4:51:09 PM

Ideally what you want is an almost exact balance of CFM capacity between intake and exhaust fans. In fact, of course, when operating there WILL be a balance - "What goes in must come out!". In planning, however, it is impossible to get an exact balance. Nearby restrictors of air flow change the actual throughput of any fan. One of the most obvious is the dust filter that you really SHOULD mount at any air intake point, be it a fan or just a grille opening. The practical problem for the design phase is that you cannot quantify how much each of these will reduce fan throughput.

One of the best suggestions I received in these forums on the topic was on how to know the real net air flow once it is operating. Light a simple stock of incense which gives off a small stream of smoke. Hold it near the case at various locations and observe which way the smoke goes - that's the air flow pattern at that spot.

Personally (and I KNOW some agree with me and others do not!) I prefer to arrange to have a slight positive pressure inside the case (that is, more intake capacity than exhaust). My argument is that you can filter dust from the intake air and ensure all the air entering is cleaner. If that flow also is in slight excess, the small outflow of air at all of the unavoidable leakage spots will prevent entry of dust. I also believe that air MOVEMENT is by far the dominant factor in cooling. The old "hot air rises" etc. themes have almost no impact on heat removal, compared to the impact of air velocity over a hot surface. This has the further implication that any air that is not moving because of barriers in the vicinity is doing little good for heat removal.
January 29, 2010 12:19:37 PM

i figure it was a small oversight when I was putting together this build. didn't really think much about the direction of the CPU cooler AND air-flow.

so, to cut to the chase, I spent $32 and bought me:
- Cooler Master Hyper 212 Plus - will allow me to point the fan towards the case exhaust fan
- Arctic Cooling MX-2 TIM - everyone and their brother has told me to use this stuff over the Dynex TIM I bought at Best Buy, so on the Hyper 212+ it'll go on as per the best recommended method I've found: spread into all cracks, clean-up with razor, then add thin lines along the pipes, install.

My current ambient temps in the room are 68-70F/20-21C - so its reasonably cold here - its winter and it's anywhere from the single digits to ~30*F outside.

With the Xiggy HDT-s1283, the best temps I've seen (with case side vents closed) was 28C @ idle, and 50C @ full load (~2C less than with case vents open).

I'm hoping with the new cooler/TIM config that the temps with either be the same or less and once a GPU goes in, I hope they stay relatively low.

I think once I do install a GPU, I'll check temps with and without the rectangular case side vent open.

After this experiment, I'll come back and see whether or not changing/adding higher performance fans to the intake or exhaust will further improve cooling.

Also contemplating whether or not to move my hard drive further up in the rails and unblock the front case intake - or leave it as-is to take advantage of the in-coming airflow to keep it cool. Current hard drive temps are reporting ~27C.

My ultimate goal is to get this thing as cool as possible without sounding like a jet engine so that in the heat of summer it isn't frying. We can hit 80-90*F inside the apartment here during a hot summer day.
a b ) Power supply
January 29, 2010 12:26:48 PM

After the GPU's in place and you look for temps, be careful which temps you examine. The impact of blocking or leaving open the lower rectangular vent likely will be most important on the GPU temp itself, and less so on the CPU. So base your decision on the GPU temp if it is available.

My speculation on the HDD position and temp is that it is fine where it is. The temp you have on it now looks very good, and realistically those units don't consume much power and generate much heat. The drive position, however, may have an impact on air supply to the CPU area and hence on its temperature.
a c 248 ) Power supply
January 29, 2010 12:28:09 PM

The temperature readings you originally posted are actually very good. The second set of temperatures with the Hyper 212 are also very good. In fact, at full load that's about as good as it gets. However, I am curious to know which cpu you have.
January 29, 2010 12:34:13 PM

Paperdoc: I'll leave the hard drive where it is. I will check the GPU temps after I install it. It's gonna be a HD 5770 hopefully.

JohnnyLucky: I have NOT yet received or installed the Hyper 212+. So, the numbers I've recorded so far have been with the as-pictured, Xiggy HDT-s1283 on a Phenom II X2 720 BE that I've overclocked to 3.6GHz at 1.45vdc.
a c 144 ) Power supply
January 29, 2010 3:13:19 PM

Paperdoc said:

... and realistically those units don't consume much power and generate much heat.

Not true. Without cooling air, the drive temperatures can go past 40 C. That doesn't sound like a lot compared to a CPU or GPU. But temperatures like that can prematurely kill a hard drive.
January 29, 2010 3:36:32 PM

FYI, from Western Digital's specs on my drive:

Temperature (English)
Operating 32° F to 140° F
Non-operating -40° F to 158° F

Temperature (Metric)
Operating -0° C to 60° C
Non-operating -40° C to 70° C
February 5, 2010 11:27:58 AM

ok, just installed the CoolerMaster Hyper 212+ last night, used MX-2 by spreading it into the cracks between the aluminum and heatpipes with a razor, then put thin strips of TIM on the heat pipes about 1/2" long ...

in HWMonitor I'm getting:

CPU: idle 27-28C, full load with Prime95, 4 threads blended 51C peak, hovers around 47C

These results are about 2-3C cooler than my Xiggy HDT-s1283 with Dynex ATIM spread on the cooler as a thin layer using the included plastic card.

It's marginally cooler, byt I'm not "thrilled" with the results, and I'm suspecting that maybe I could try a different TIM application method.

However, I supposed since the CPU fan is now blowing through the heatsink and into the suction path of the case exhaust fan that this will really pay off when I install a discrete GPU...since it won't be blocking the sucktion side of the CPU fan like it would have with the Xiggy.

I'm debating about getting a higher CFM exhaust fan, but am not sure.

I also backed the OC down, now running at 3.5GHz since when I ran Prime95 for a few minutes, the system restarted. I may try and back the voltage down to to see how low I can go and keep the frequency up while running P95 for several hours.

I had been at 3.6GHz (18x), and 1.45vdc...I didn't really want to go higher since I intend to keep this machine for a while, so longevity is important and I don't really need to overdrive this thing to the max.
February 15, 2010 1:28:34 AM

any other advice?

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a c 248 ) Power supply
February 15, 2010 2:18:49 AM
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darkfa - As previously mentioned the temps are about as good as it gets. I got the same/similar temps at full load with an original Hyper 212 in a Coolermaster HAF 932 case mod I sold, my own HAF 932 with an original Thermalright Ultra 120, and my brand new Lian Li Dragon Lord case with a brand new Thermalright Venomous X.

There is a point of diminshing returns. We've reached the practical limits of air cooling. There is no need to change anything.
February 15, 2010 11:13:56 AM

Best answer selected by darkfa8.
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