Exterior ducting of 120 mm fan

[imported_stev]

My computer desk has a section for a normal-sized computer case in it, but the back except for the botton 10 inches is enclosed. This has been fine in the winter, but as ambient temps have risen recently, I've noticed that my CPU is around 45 C idle and I've seen it reach 65 C under stress!!! I'm not overclocking, btw.

When I put my hand around the case, the air does feel pretty warm so it's obviously not getting enough ventiliation. The rear 120 mm fan blows directly onto the back of the desk with about 4-5 inches of clearance, with the hole in the back being a few inches below the fan.

I could probably solve this by cutting out more of the desk, but I'd rather solve this particular case's issue with the hope that computers down the line will be so energy efficient that they will hardly put out any heat. I'm wondering if there's any ducting available out there for a 120 mm fan that I could attach to the back of my computer that would be somewhat flexible and maybe a couple feet long that I could use to blow the hot air clear of the desk?

Cliffs
-CPU temps are high due to the case being mostly enclosed in a desk
-Would like to buy ducting that can be attached to my case's 120 mm fan outlet to blow air clear of the desk
-Any product recommendations?

 

[zagood]

You can go down to Home Depot, Lowes, wherever and find dryer ducting. Sunbeam has a kit you can buy with mounting if you want to be lazy.

Do you have an intake fan or fans? If so, you're not going to see any real performance changes if you duct the back. That warm air will eventually get out of there, and if you've got fairly even pressure in your case it's not going to get sucked back in; unless the front of your desk is closed, with a door or something like that. In which case you should worry about getting fresh air to the front instead of the rear.

Also, with ducting, the fan that's ducted will have to work harder to push the air through the duct. Not that much more, but enough that it may actually have a negative effect on temps and/or sound. You could attach another pulling fan to the end of the duct, which would negate the difference, but you'd add the sound of another fan.

EDIT: If you REALLY want to do something like this, here's an idea. Cut a hole about the size of the duct in the back of the desk directly behind where the exhaust fan is. Duct directly to that. Mount a fan on the desk side if necessary. Of course, don't forget that it's there, otherwise it's going to get messy when you pull your computer out.

-z

 

[imported_stev]

The front has an 80 mm fan blowing on the hard drive cage and the front of the desk is completely open.

I just thought of something... This same case with a similar cooling setup had a 3500+ in it before and the temps were fine. I figured that the 4600+ was just much hotter, which could partially be the case, but perhaps I damaged the thermal pad when I installed it (It did take me awhile to get the heatsink on, lots of movement on the CPU)? The last time I turned my computer on after it had been off all night, I'm pretty sure the CPU was in the mid 40 C range by the time Speedfan loaded. It would seem to me that if it was a ventilation issue it would take longer for the heat to build up around and inside the case. I've never done it before, but maybe it is time to try some arctic silver? I'll pull the case out of the desk and see if my temps drop significantly. If they do, I'll try ducting. If not, I hope a vial of AC5 does the trick!

 

[NickelPlate]

Sounds like alot of trouble that I'm guessing that probably won't work so well. A 120mm fan even on high doesn't really move that much air to think about pushing it through 2 feet of ducting. You'll lose efficiency and will likely cause back pressure on the fan, try to keep it as short as possible. You could attach a second 120mm at the end of the duct to really move the hot air out and away from your PC (push-pull configuration), and point the duct upward a little to get some help from convection.

A better solution would just be to find less restrictive location for your PC. I've got one of those enclosures on my desk too and had the same problem. I just moved the PC to the desktop.

 

[imported_stev]

I hate the duct idea too, but I just can't bring myself to set the computer elsewhere and have a big, gaping spot where a computer should go. I would consider getting rid of the computer and buying a more efficient one before I do that.

 

[Zepper]

You might find something in these duct fittings pages that would work for you - lots of the items are available at the big-box home-improvement stores like Home Depot, Lowes, etc. Or you could just cut more of the back away. The Sunbeam duct kits are only good for 80mm fans. But there are others out there. One can connect to 70 - 90mm fans.
And maybe these guys Performance PCs have something you can use - if the duct isn't considerably larger than the diameter of your fan, consider putting another exhaust fan at the outside end of the duct.

.bh.

 

[SRoode]

If you are thinking of buying a more efficient PC (reading, less powerful), you can do that for free with what you have. Try lowering the multiplier on your CPU from 12 to say 10 or 11, and check temps. With the lower multipler, you will generate less heat, and may not notice the speed difference. Afterwards, you could even lower CPU Core Voltage from 1.35 to say, 1.275 and get even less heat.

 

[imported_stev]

I would consider a more efficient PC one that does the same amount of work, but with less heat. From what I understand, this can often come from a CPU doing more in a clock cycle, which allows it to have a lower clock speed and CPUs that use smaller processes (65 nm instead of 90 nm) won't generate as much heat. So, I would not underclock or undervolt.

 

[zagood]

but perhaps I damaged the thermal pad when I installed it

I'm hoping you didn't use the same thermal pad as the old processor, and you properly cleaned the old gunk off first with high purity alcohol or something like that.

Probably a good idea to re-install the heatsink. Follow the instructions on AS5 and you'll probably see better results.

-z

 

[SRoode]

Originally posted by: stev
I would consider a more efficient PC one that does the same amount of work, but with less heat. From what I understand, this can often come from a CPU doing more in a clock cycle, which allows it to have a lower clock speed and CPUs that use smaller processes (65 nm instead of 90 nm) won't generate as much heat. So, I would not underclock or undervolt.

Sorry, I thought you were looking to keep what you had, and maximize lifespan. If what you said is the case, I would just keep doing what you're doing till your CPU burns out (if it ever does). If you are looking to upgrade to a CPU that does the same amount of work, but with less heat... Why upgrade now? Burn it out.

By that time we'll be 3 or 4 CPU generations ahead.

 

[imported_stev]

Originally posted by: zagood

but perhaps I damaged the thermal pad when I installed it

I'm hoping you didn't use the same thermal pad as the old processor, and you properly cleaned the old gunk off first with high purity alcohol or something like that.

Probably a good idea to re-install the heatsink. Follow the instructions on AS5 and you'll probably see better results.

-z

Both the 3500+ and 4600+ used their respective stock coolers with the factory thermal pad on the heatsink. I will make sure to to clean everything thoroughly before using AC5 (and I did look at those instruction today already, so I'm all set!). I even got the two step cleaner from AC. Yeah, it's probably a marketing ploy, but I'll try it out.

Originally posted by: SRoode

Originally posted by: stev
I would consider a more efficient PC one that does the same amount of work, but with less heat. From what I understand, this can often come from a CPU doing more in a clock cycle, which allows it to have a lower clock speed and CPUs that use smaller processes (65 nm instead of 90 nm) won't generate as much heat. So, I would not underclock or undervolt.

Sorry, I thought you were looking to keep what you had, and maximize lifespan. If what you said is the case, I would just keep doing what you're doing till your CPU burns out (if it ever does). If you are looking to upgrade to a CPU that does the same amount of work, but with less heat... Why upgrade now? Burn it out.

By that time we'll be 3 or 4 CPU generations ahead.

HD temps are fine and it's the data that I really care about. Still, I'd like to cool it down AND not have to undervolt. I'm greedy like that.

Anyway, I pulled the machine out of the desk and wow, it still idles around 37 C (EDIT: but more striking is that it still gets to the high 50s under load!)! That seems high, especially since it's not that hot in the room. So, I think I'll try some AC5 and see if that helps.


Thanks everyone. I'll update you guys later.

 

[NickelPlate]

Those temps dropped quite a bit though from your original post (8°C or so) so taking your PC out of the enclosure did help. Also a single 80mm intake fan IMO is pretty weak. Do you have any other openings to add another intake fan? You could nibble or holesaw a hole on your side panel inline with your CPU and add an 80mm or 120mm blowing directly on the CPU (this will do wonders for your proc temps as I've done it before).

It sounds like the problem is just a function of three things: Being in a restrictive location, not enough intake, and warm summer weather. What's the temperature in your room?

 

[imported_stev]

Originally posted by: NickelPlate
Those temps dropped quite a bit though from your original post (8°C or so) so taking your PC out of the enclosure did help. Also a single 80mm intake fan IMO is pretty weak. Do you have any other openings to add another intake fan? You could nibble or holesaw a hole on your side panel inline with your CPU and add an 80mm or 120mm blowing directly on the CPU (this will do wonders for your proc temps as I've done it before).

It sounds like the problem is just a function of three things: Being in a restrictive location, not enough intake, and warm summer weather. What's the temperature in your room?

The 80 mm fan is really just for the HDs and it made a huge difference in their temp. The case will handle one more 80 mm fan up front, but I'm not sure the cooling will justify the noise.

I have an opening and a short duct that ends close to the CPU that can take a 92 mm fan. I could try a fan in there, but it seems funky having the heatsink fan and that duct fan blowing against each other. But if you say it's effective it's worth a shot (already have the fan!). I guess any extra circulation will help in this case even if you're not blowing air in a specific direction.

Room temp is probably low 70s F. I'm in Seattle, so we're not talking about an extreme summer, but the room temp can fluctuate by as much as 10 F during the year.

Thanks for the suggestions.

 

[NickelPlate]

Originally posted by: stev

Originally posted by: NickelPlate
I have an opening and a short duct that ends close to the CPU that can take a 92 mm fan. I could try a fan in there, but it seems funky having the heatsink fan and that duct fan blowing against each other.

What CPU cooler are you using? When you say blowing against each other do you mean the fans are going to be blowing in opposite directions? That's not what you want to do. If your CPU fan is a front to back blower, or a top down blower (toward the MB) it will work. The extra side fan should be used as an intake, taking air from the outside and directing it on the CPU cooler.

 

[Noubourne]

Originally posted by: stev
I could probably solve this by cutting out more of the desk, but I'd rather solve this particular case's issue with the hope that computers down the line will be so energy efficient that they will hardly put out any heat.

LOL!!

Get out the skillsaw.

 

[imported_stev]

Originally posted by: NickelPlate

Originally posted by: stev

Originally posted by: NickelPlate
I have an opening and a short duct that ends close to the CPU that can take a 92 mm fan. I could try a fan in there, but it seems funky having the heatsink fan and that duct fan blowing against each other.

What CPU cooler are you using? When you say blowing against each other do you mean the fans are going to be blowing in opposite directions? That's not what you want to do. If your CPU fan is a front to back blower, or a top down blower (toward the MB) it will work. The extra side fan should be used as an intake, taking air from the outside and directing it on the CPU cooler.

I'm using the stock cooler that came with the 4600+. Yeah, I guess I keep forgetting that the CPU fan is blowing down through the heatsink, not up away from the heatsink. Anyway, I tried mounting the 92 mm fan as an intake and it didn't seem to change the temp much, if at all. AC5 arrives today (hopefully) so I'll see what the does for me this weekend.

Originally posted by: Noubourne

Originally posted by: stev
I could probably solve this by cutting out more of the desk, but I'd rather solve this particular case's issue with the hope that computers down the line will be so energy efficient that they will hardly put out any heat.

LOL!!

Get out the skillsaw.

Well, I had zero problems with the 3500+ (even during last summer) in the same machine. So, for example I think a mid-level C2D system would solve my problems. But yeah, I get your joke