View Full Version : Help with airflow
I have been fighting a heat problem since this summer. I have a 1333 TBird @ 1500, 10x 150. I was running a Glaciator and the temps had been 43 to 45 @ idle, and then 48 to 52 @ full load. Not good temps but liveable. I just attributed it to the hot summer. I just got an Alpha 8045 with a 39cfm Sunon (Hate noise) and was really surprised at the results from it, 44c @ idle, 48c at full load. Full load was done bu looping Sandra burn-in until max temp was achieved.
Now for my theory. It suddenly dawned on me that my heat problems also coincided with switching to an Enermax 431 dual fan psu. With my KK266 m/b the hsf is at the very edge of the board, hence right next to the bottom intake fan on the Enermax. With my CasEdge case the distance involved is less than 1/2 inch with the 8045. Is it possible that the psu fan is interferring with the airflow enough around the hsf units to limit their cooling ability? There is an 80mm fan in the bottom front of the case sucking in and also another 80 in the left side directly across from the hsf. I have tried this sucking and blowing. The Alpha works best with the hs fan sucking and the other 80 sucking air away from the hsf.
Anyone have any thoughts?????
Intraveinous
11-16-01, 10:30 AM
Do you have a big drop in temps if you run the case with the side off? You may consider putting a ducted blow-hole in the side of your case, feeding outside air down to the heatsink and surrounding areas. This should eliminate any problems you could have with less than optimal airflow around the heatsink.
Peace
John
Actually it is just the oposite with case open. Temps are 2c higher. I did have a getto duct running to the Glaciator as with the Gladiator before that. Temps came down around 2c with the duct. The Alpha temps are higher if the fans are set to suckin outside air and blow over the heatsink. I don't think the 80 case fan is enough to supply the Sunon on the Alpha so I did not try ducting it. I did order a Panaflo 47cfm for the Alpha and a 92mm 56cfm for the case to try that out. Then this whole idea of the psu interferring with the hsf came to me. My daughter is going to come and look at the setup and consult me on it. She is a Systems Design Engineer with an aircraft company and has had few classes in Thermo dynamics and airflow and such. I think it will be funny if my problem all along was not hsf related.
hlminpdca
11-16-01, 11:00 AM
if you introduce room temp air via duct (2 words) you will see a drastic reduction in cpu temps. And yes I came to the same conclusion about the 92mm fan on my Enermax. For me it was even more of an issue, since I was using a Silverado heatsink which has those little blowers. The blower was facing the 92mm fan.
DON'T TOUCH ANYTHING INSIDE THE PSU BESIDES THE PLUG FOR THE 92MM FAN. IF YOU DO YOU COULD END UP OVERCLOCKING YOURSELF.
unplug your PSU for about 6 hours. Right after you unplug it hit the power button to suck some more juice out.
take the psu out of the case. There is about 2 or 3 screws where the exhaust & plug are, and there are probably a couple more on the top of your case. Then unscrew the four little screws that hold the side with the big label on the PSU. The side should slide right off.
Using tweezers or needle-niose, pull the connector for the 92mm fan off of the PCB connector inside the PSU. Run this out of the PSU if you can make a hole big enough in the grill that is facing the front of the case to get it out. You should probably do this if you are putting alot of extra strain on your PSU besides components. If not just secure the plug and wire somehow, or run it out of the fan opening. If you decide that you need to run the 92mm fan, than run it out of the psu through your widened grill area, and plug it into a power connection of 7Volts. I have a 6 Volt connector lead from the Silverado. But some say that this 7 Volt trick may cause problems with your psu. But if you do this your 92mm fan will slow down, quiet down, and allow your PAL 8045 to do a better job. The connector is 2-pin type, but you can make it fit a 3 pin connector, just make sure you match the colors up.
The whole thing is very screwy. This 92mm fan on my unit was trying to move so much more air into the PSU than the 80mm exhaust fan could possibly expel. There was hot air spilling out of the grill in the front back into the case. So I unplugged it. Everything is fine.
Just be sure to put the temp sensing lead (if your fan has one) from the psu exhaust fan in a hot place (like the PSU) so that it runs fast. If you were to partially/fully block the hole where your 92mm fan was moving I would think that it might actually help to guarantee that all the heatsinks in your PSU get a share of the air flow.
have fun. don't electrocute yourself.
The first thing I am going to try is putting the old psu in and comparing the temps. I take it that there must be some capacitors or such that hold a charge inside the psu. What is the lead that is a black and white wire that has a plug that fits on a "male" fan lead that comes out of the Enermax? I plugged it into the psu fan header on my KK266 but it does not monitor fan speed.
hlminpdca
11-16-01, 11:58 AM
you have it plugged in right?? On my Enermax 365P(VE)FC, that is the 80mm exhaust fan's power. you need that.
Yes, it is plugged in still.
AstronMike
11-16-01, 09:34 PM
Hmm, my cpu is right near the bottom of the PSU too, and Im also running hot regardless......wonder if I made a duct outta foamboard and used a sunon 120 to blow in directly to the sink??
Will try this tomorrow and post the results..
hlminpdca
11-17-01, 02:24 AM
the most important point with slowing the fan down is that the original setup just doesn't make sense. At least in my Enermax it was set so that the 92mm fan was way too fast for the 80mm exhaust fan. Not necessary and blows hot air back through the front of the PSU.
I think the fact that my Silverado had blowers which one of them was facing the 92mm fan , and pretty close definitely gave me a reason to expect improvement there. But in a traditional setup I can't be sure how much effect it will have.
But using room temp air to cool your CPU will make a good amount of difference for sure.
I got home late last night and the only thing I tried was I place a PCGamer bonus cd on top of the Alpha which pretty much blocked the air from the 92 on the Enermax. The psu temps then fluctuated betweeen 1c lower and the same, but the m/b temp dropped 2c. I am going to try now changing back to the original psu. Will post results when done.
Here are the results from switching psu.
Enermax with 92mm in bottom - 23case, 51 cpu, 29 m/b
Stock 235w psu, no bottom opening - 22case, 49 cpu, 28 m/b
I tried to get the readings as close together as I could but I think that the room temperature has actually risen a few degrees. I guess I shouldn't have put wood in the stove.
I have already got the 92 unhooked and the wire out the back, ready to put back in and try it vs the standard. Also will have to see if I can find an article on how to get the 7v mod off the 12v connector, as I have seen that before. But have a honey-do to do at the moment. Dam drain is clogging and my wife seems to think that is more important for me to do. Go figure ;)
Here is something that I did. Help do lower temps about 5 degrees.
Rob
hlminpdca
11-18-01, 03:21 AM
so you just took the whole side off of the PSU? Is that what I am seeing?
I'd be too afraid to do that.:(
another cool mod for the enermax would be to flip it over, and flip the 92mm fan around. cut a hole in the top of your case, and remove the grill at the front of the psu. This would use the 92mm fan as an exhaust fan, you would have the 80mm, and the 92mm exhausting air from your case.
All this is very interesting. For the past few months I have been playing around with fans etc. & found the best combo. was a Alpha 8045 blowing air onto the cpu with a fan directly in line to the H/Sink (On side panel) also blowing air into the same area.I had a fan blowing in on front & a fan sucking @ rear. Total 4 fans
Temps. 39C idle / 42C load. (M.Board 26C)
I just got an early Xmas present from my wife a Antec SX8300 I have installed 2 rear fans (sucking out air) 2 front fans (blowing in air) same Alpha 8045. Total 5 fans
Temps. 44C idle / 46C load. (M.Board 23C)
So to some it up I`ve got a great case ( BIGGER ) but running hotter.
The smaller case ran cooler on cpu but hotter on M.Board
Acko
Originally posted by hlminpdca
so you just took the whole side off of the PSU? Is that what I am seeing?
I'd be too afraid to do that.:(
.
All I did was take the top cover off the power supply. (it's already filped upside down)
Rob
Acko, I just ordered a 1000 series SOHO Server case by Antec. It is similar to the 830. It will have 2 80's in front and 2 80's in back. I noticed on your new case you did not mention if you also put a fan in the side blowing at the hsf. I plan to up the 39cfm I have on my Alpha to a 47cfm and put in a 56.7cfm 92 ducted to it similar to your first setup. The added height of the SOHO case should cure the fan interference problem I am experiencing now. At least I hope so.
hlminpdca
11-18-01, 05:15 PM
I don't see the smart guy with the beard around anywhere, but... The same amunt of air will move faster through a smaller space. I think. Increasing the amount of fans in a bigger case must be done, but it isn't necessarily going to give you cooler temps. Bigger house, bigger AC unit and furnace?
I think you are missing the point with which I started this. The case I have now is short enough that it puts the intake fans on the bottom of my Enermax psu right on top of the Alpha. It is also not very weel designed for airflow, the only way to exit air is by the psu or you could put a 60mm fan in the back. I did experiment with a couple but they were load as heck. The articles I read on the Antec case all commented on the air flow and cooling properties of it. And yes it does take more fans but the Antec is designed for 4. I don't think I have ever read anywhere that a smaller case will be cooler, but I could have missed that one.
hlminpdca
11-18-01, 11:58 PM
pntgrd, I was trying to shed some light on acko's post as to why it is possible for a bigger case to be hotter. sorry if there was any confusion there.
Sorry, I misunderstood you. I would think it could be tha abscence of the fresh air duct to the hsf, if that was the case nad he hadn't done it on the second case.
Can someone elaborate on flipping the PSU or removing the cover? Robbie, was it your mobo or CPU temps that dropped when you did this and by how much exactly? My CPU runs around 40C and the mobo is at 26C (2 above ambient) now with colder weather here, but I'd like the CPU to drop to mid-30s. I've got an Antec 300 watter.
Hi Pntgrd
You must of read my mind I have been thinking about the side fan since I set up my new case! Luckily I have access to sheet steel & am going to make up a mock side panel with holes etc. Just like I did with my old case. But remember this new case was a Xmas pressy from my wife I`ll have to be diplomatic so as not to upset her.
Temps to-night are better 21C M/Board / 42C cpu room temp 66C
Acko
Originally posted by zap3v
Can someone elaborate on flipping the PSU or removing the cover? Robbie, was it your mobo or CPU temps that dropped when you did this and by how much exactly? My CPU runs around 40C and the mobo is at 26C (2 above ambient) now with colder weather here, but I'd like the CPU to drop to mid-30s. I've got an Antec 300 watter.
Well in my case the power supply is mounted upside down. I figured that I would get better airflow if I took the cover off the power supply. My case temps were REAL close to the 90's, I just check it and my computer has been on for a few hours and it says it's at 80 degrees.
The Cpu will also drop in temps cuz the air around it is cooler.
Pm me if you need any more info.
I'll be glad to help
Rob
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