Bad airflow / case layout bad?

shantaram.nz · Post by **shantaram.nz** » Mon Mar 10, 2008 4:56 pm

My rig:

E6850 Intel C2D on Asus P2B.
Asus triton 75 HSF with Nexus 120mm fan (blowing down)
8800GTS 320MB Video card stock cooler
Chenbro Gaming Bomb case with 92mm Front intake / 120mm exhaust Nexus fan's.
Silverstone Element ST50EF 500w PSU

I am running speedfan 4.33 latest non beta release and am taking temperatures from Core temperatures and have adjusted them +15 to reflect the correct temperature as reported by CoreTemp.

I recently upgraded the stock Intel HSF for the Asus Triton 75 one on recommendation from Recommended HSF section here at SPCR. Love the noise difference the change has made but am thinking my temperatures seem a little high.

I have included photos of the pretty cramped hsf/psu section of my case and am looking for comments or advice as to what I have, whether it is suitable or a bad layout i.e too cramped and effecting my temperatures.

What are average idle/load temperatures for the 6850 with a reasonable aftermarket cooler? I am using the stock thermal compound that came with the HSF from Asus, seems hard to spread a reasonable and even coverage of paste as it is very thick and sticky... and this could possibly be effecting the heat transfer but just a guess.

1 On startup the Core is running at about 32 to 35ish.
2 Just browsing internet etc I am idling at 40-42 after about half an hour.
3 After 3 hours of online gaming with machine running 3d graphics, I saw my machine hitting as high as 77. I am a bit worried, this seems pretty high to me.

*Quick update*
Just ran Prime 95 for less than 10mins and temperatures rose to 89C in that time and I dont think were fully finished!

I know this isn't very comprehensive testing, I plan to do some more formal testing.. but was hoping that initially I might be able to get an idea whats happening.

Many thanks in advance, I'm pretty nub so if I left something out please let me know.[/img]

surfntom · Post by **surfntom** » Mon Mar 10, 2008 6:06 pm

a quick fix would be to put the exhaust fan on the outside of the case. that cofiguration seems like it would be very noisy so you should hear a large decrease in noise by moving your exhaust fan.

shantaram.nz · Post by **shantaram.nz** » Mon Mar 10, 2008 6:19 pm

Ok I will look into that, the noise isnt so bad when I set it to about 70% speed, its almost silent to my hearing.

More concerned with heat presently.

LongJan · Post by **LongJan** » Mon Mar 10, 2008 7:17 pm

I can see three 120 mm fans competing about the same air.

Two 120 mm fans for exhaust, I suppose you have more intake than that 92 mm in the front, perhaps side vents.

Why not try to let the back fan blow fresh air in to CPU and PSU and the fron fan suck out some of the heat from the VGA card. I have such an airflow in my mATX case and everything is quite cool.

shantaram.nz · Post by **shantaram.nz** » Mon Mar 10, 2008 7:23 pm

No side vents, one front intake fan only. Hadn't considered changing the directtion of airflow, but its going to mean warm air being exhausted out the front of the case (past the hdd cage). Currently its a typical arrangement with front bringing in cool air past hdd and video card, warm air rising and exhausting out the back chassis fan and via psu.

tehcrazybob · Post by **tehcrazybob** » Mon Mar 10, 2008 9:12 pm

I think LongJan is onto something. That exhaust area looks extremely cramped, and it looks like you have a 120mm PSU fan, 120mm case fan, and rear-vented video card all pulling air out of the case, with only a little 92mm pulling air in.

If you stick the rear 120mm fan on the outside blowing in, and reverse the intake fan so it's blowing out the front, I think you'll do a lot better. The airflow will be a lot more balanced and free-flowing.

Don't worry about the typical layout - convection (heat rising) is irrelevant with even the very gentlest breeze. It's a good suggestion most of the time but in your case might not be the best approach.

JaYp146 · Post by **JaYp146** » Mon Mar 10, 2008 9:36 pm

OP, I had a very similar situation in my Antec SuperLANBoy a couple years ago.

Had an XP-120 with a Yate Loon, Sunbeam NUUO 550w, and Antec Tricool 120mm all within close proximity. Said proximity resulted in the majority of the CPU's hot air being exhausted through the power supply.

Unfortunately, this rush of constant hot air ended up killing the power supply (blown cap).

So yes, look into fixing your predicament. Maybe an extra intake fan, custom duct?

shantaram.nz · Post by **shantaram.nz** » Mon Mar 10, 2008 10:00 pm

Interesting idea, I will look into this in the next day or two and see how things turn out. Thanks.

nyu3 · Post by **nyu3** » Tue Mar 11, 2008 6:31 am

You could change your case to one with power supply at bottom. For example:
1. Antec Three Hundred (~$90) With this case, I would leave out the back exhaust (maybe even block it) and use only the top exhaust + a 120mm intake fan.
2. Coolermaster 690 (~$75) This case has side holes directly in front of your heatsink. Also, the top is perforated to exhaust heat.
3. Antec P182 (~$100) Classic
4. Lian-Li makes quite a few cases with power supply on bottom or "inverted motherboard" Most of them are quite exepensive, so I didn't list them here. One of the more intriguing Lian-Li's is the PC-A05

Another option is to mount your power supply upside down, then cut a 120mm hole on top your your case to provide fresh air for the power supply.

Otherwise, go for a heatpipe tower type heatsink like Ninja or Ultra-120 Extreme.

shantaram.nz · Post by **shantaram.nz** » Tue Mar 11, 2008 7:40 pm

Longjan I have tried what u recommended. Now have one 120mm intake fan at the rear and one 92mm exhaust fan at the front. Currently I have the fan on the hsf blowing down on the hsf and board as per the review of this hsf here at spcr.

My core0 and core 1 temps are sitting steady now at 74C while running the prime95 test for about 30mins (small FFT - fpu intensive). So theres some improvement already thank you.

Do you think its advisable to try reversing the fan on the hsf, to exhaust heat off the fins rather than blow down on board?

Is this temperature 74C high for a stress test like prime95, I never tried it with the stock fan to compare. This temperature is adjusted +15 in speedfan to match CoreTemp temperatures.

Thanks

shantaram.nz · Post by **shantaram.nz** » Tue Mar 11, 2008 7:42 pm

Thanks for case recommendations, at this stage I'd really prefer not to buy another case or make modifications like cutting steel etc as its outside my toolset/skills for now. Hoping to get a suitable solution with what I have first, and if that fails I will resort to 'other' options, but many thanks!

LongJan · Post by **LongJan** » Tue Mar 11, 2008 9:47 pm

I don't think that direction of the CPU fan matter much.

You could try to improve airflow a bit further (without cutting) by removing a couple of PCI slots below the VGA card, but that will probably do more for the GPU than the CPU.

The on core sensors reports the difference between actual temperature and TjMax. Nobody seems to know TjMax for sure, but I think CoreTemp calculates with 100C. That means that you have 26C left to the throttling point, not too bad.

Normally, I suppose you dont't play Prime95 but some game (according to your VGA card). When I am playing World in Conflict my core temps stays 44C below TjMax, but that is with the cooler E4400 and 8800GT and 120mm front fan with no blocking harddrive and side vents and open PCI slots...

FartingBob · Post by **FartingBob** » Wed Mar 12, 2008 7:28 am

LongJan wrote: The on core sensors reports the difference between actual temperature and TjMax. Nobody seems to know TjMax for sure, but I think CoreTemp calculates with 100C. That means that you have 26C left to the throttling point, not too bad..

Off topic, but since you brought up the tjmax thing, why does intel do it this way? Rather than just report the actual temp instead of subtracting the temp from tjmax? And why dont they release the exact tjmax for each CPU? I cant see that it would negatively effect intel's business, but help keep the OC'ers happy.

LongJan · Post by **LongJan** » Wed Mar 12, 2008 11:15 am

Well, actually they report the most important value, what margin you have until throttling occur.
In a way, one could think, that if that margin is safe, never mind the actual temp.

tehcrazybob · Post by **tehcrazybob** » Wed Mar 12, 2008 1:52 pm

LongJan is right. If you know the current temperature, you still have to look up the maximum for the processor and remember it, in order to know whether you are safe. The way Intel is doing it is more informative, and only irritates the people who are used to knowing exactly how hot their processor is. This way, a single number tells you not only whether you are safe, but also how safe you are. There's no longer any need to know what the chip is actually safe at. And really, have you ever needed to know what the actual CPU temperature is? I can't think of a situation where you would.

shantaram.nz · Post by **shantaram.nz** » Wed Mar 12, 2008 10:26 pm

Well I decided to put the fans back into the original direction at the start, as after running the pc for a few hours incorporating LongJan's reverse fan directions idea, it was extremely hot inside the case around the video card and the hdd was quite hot to touch, all alot hotter than before and definitely not healthy I would imagine for the components. With the case front off I dont think it would have been as bad, but the air just wasn't excaping with it on.

I have rigged up the 12cm exhaust fan outisde the case temporaril, but the noise is surprisingly louder than when it was inside, but I guess theres a little bit of room there now where some air can move around.. so better in that regard. Still I'm back where I started now.. maybe I should be happy with the temperatures, sure the core temp is hitting 80C when im running prime 95, but it isnt getting close to that when running real world apps, game etc.

Post by **MikeC** » Wed Mar 12, 2008 11:35 pm

Try removing the cover off one of the unused CD bays. Hopefully you have one free, fairly close to the top. This will be another intake path to help the case breath better. If it improves cooling, then you can just find a thin piece of sponge (black packing open cell foam will do fine) not more than about 1/2" thick in place of the CD bay cover to use as dust filter / cosmetic measure. If that blocks air too much, try different thicknesses or open up a second CD bay the same way.