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BH

Burke Hamblin

22 Posts

88763

December 23rd, 2004 14:00

Dimension 4700 heatsink/fan question...

I received my Dimension 4700 yesterday (3.0 Prescott), and I noticed the fan for the "green chimney" is actually taking in air from the rear and blowing it over the skivved fins instead of drawing heat off the heatsink and moving it out the back. After seeing the perforations on the side panel, I assumed it was done on purpose, but I just wanted to make sure the fan is facing the proper direction and that it's not an assembly mishap. TIA.

BH

firefox91

21 Posts

March 2nd, 2005 19:00

Well I have been running my system for a few days now with the fan setup I mentioned above and have had zero problems. Even while running my GeForce 6600 on a game the system remains nice and cool. I can't even feel any noticable heat on the outside of the case where the video card is located. I truly believe some of the 4700s are being assembled wrong when the case fan is blowing into the computer. If you think about it, the whole purpose of the green tunnel is to make sure air gets pulled over the heatsink and out the case. If it wasn't there, the fan would end up pulling a lot of air around it and a lot less over the heatsink. If the fan was supposed to be blowing in over the heatsink, what do you need the tunnel for? It is directly in the air path so it would get plenty of air. And then, where is this hot air supposed to go?

firefox91

21 Posts

March 19th, 2005 13:00

Hmmm... posting size limitation. :)

To continue...

I added a slot fan from CompUSA into the last slot above the PCI-E x1 connector since I will not likely use it anytime soon. That's it.

I did not add any side fans because they are not needed in this case and would probably just disrupt the airflow I created.

wisemanhsu

12 Posts

March 19th, 2005 13:00

Originally, I had wanted to use the Zalman CNPS700B-Cu heatsink cpu fan but another Dell user posted that the retention bracket wouldn't line up to the 4 holes onto the 4700 motherboard.

So if anybody successfully got an aftermarket heatsink/fan to fit, could you please message me and let me know which brand/model you used?

I too am interested in reversing the case fan and removing the green plastic chimney, adding a fan in the front behind the bezel, and adding a fan on the side case. If anyone can provide me pictures of the modifications you've done... that would greatly help me. I sure could use a model to pattern my system after. I haven't fiddled with computers for many years, so I could use all the help I can get. ;)

Thanks in advance!

firefox91

21 Posts

March 19th, 2005 13:00

I would e-mail you pictures of what I did but I loaned my digi-camera to someone and they will be gone for a while.

As far as replacing the CPU heatsink and fan, I'm not really sure there is a need to. I honestly think that Dell's implimintation of this is very good. It does take up a lot of space but nothing else needs to go there anyway. I would recommend keeping the green tunnel as it serves a purpose as long as the fan is blowing the right way. If it is not, it is an easy fix.

Pull up the tab connected to the fan, slide down to remove. The fan is connected to the fan housing by 4 rubber posts. Just pull on the fan and the posts will let go. Take note of which direction the posts are supposed to face. Turn the fan around and reconnect to the posts and reinstall. There should be an arrow on the side of the fan indicating which direction airflow is going. Just make sure it points out the back of the case.

For the front bezel fan, just remove the front bezel. (See Dell online instructions, there is not much to it.) Get an 80mm fan and a couple of zip ties. Check that arrow again and make sure airflow is going into the case. Feed the zip ties through the screw holes on the fan and through the vent holes on the case. The fan should be centered in the middle of the case holes which will have it a little off center of the case, it will still work fine. Run the power cable up through the floppy drive mounting area (assuming you have no floppy like me) and connect to the power supply.

wisemanhsu

12 Posts

March 19th, 2005 14:00

Thanks for your reply. So by reversing the case fan to draw heat away from the cpu & heatsink, have you found this to be better than the original set-up? Could you turn your computer on, remove side pannel, carefully place your hand next to the green chimney & cpu heatsink, and without touching anything - can you feel air being drawn in?

I slightly understand the original design. The fan draws air from outside the case (the air outside should be cooler than the inside) & directs it via the green plastic chimney like an air duct directly to the cpu/heatsink. My concern with this is there is no exhaust fan to help remove the hot air. I could be wrong, but I doubt the PSU is responsible for exhausting the heat in the case. Sure, the power supply unit has a fan, but it's mainly for cooling the psu, not the rest of the case.

Sure, there are small holes/vents on the bottom of the case near the pci slots & some small holes on the side panel... (granted, I have limited knowledge of physics.. but I thought heat rises). So sure, on 1 hand, the balance of pressure could help push some heat out those holes on the bottom, but on other hand, it may help if there were a fan to help exhaust the hot air out the case.

I've read in other posts where some removed their side panel to deal w/ the hot air trapped in the 4700 case, but I would like to avoid that that option.

What if I drilled on the top of the case and put a fan to help draw air out from the top? Would that be plausible and helpful? I'm also contemplating getting an aftermarket psu that can help dissipate the hot air from the case.

wisemanhsu

12 Posts

March 19th, 2005 14:00

About the fan that goes between the bezel... So it should be okay to leave the hard drive and brackets in place? The fan may help cool the hard drive, but I was considerring removing my floppy drive and placing the HD into the floppy drive bracket... leaving the bottom unhindered. So by removing the hard drive and the brackets, the fan would have a clear path to shoot air from the bottom, eventually pushing the hot air from the motherboard, cpu/heatsink, memory, optical drives, and going w/ the heat rises theory, push the hot air up so that my new power supply unit can help draw heat out, and if I can get it to work and fit, a fan on the top of the case to draw heat out.

I was also considerring something like this -->http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=633877

But that may conflict with my initial plan.

Part of my thinking is influenced with this --> I have a Sony 19" CRT monitor. And early on while owning it, while it was on for long hours at a time, the heat generated from the back of the CRT was noticeable. Whenever I turned off the monitor, it would make a lot of sound, probably due to the electronics involved, but possibly also due to the heat. If I placed my hand near the openings on the back, I could feel a lot of heat. Well, I was able to find a 120mm fan on ebay , you place it on the back of the CRT, and it draws up heat from the inside of the monitor. Now, when I place my hand near the holes, no heat is noticeable. And when I turn off my computer, there no longer are those sounds that scare me that my computer is about to die. So this is partly what influenced me to think to take advantage of the heat rising issue and doing something to help draw heat from the top.. but of course with all the different fans that a person can add, it can cause a lot of problems with the airflow and so I'll research and experiment some more....

firefox91

21 Posts

March 20th, 2005 00:00

I think an exhaust fan on the top of the case probably would help because heat does indeed rise. But it might be overkill. Do you really want to go to the point of cutting your case for better cooling when you don't really need to? If you are planning on jamming a lot of stuff in the case then it would make sense. But if it is just a couple of extras like me (additional hard drive, Audigy 2 card, GeForce 6600) I don't think it needs it. Just my opinion.

As far as the intake fan goes, it does indeed blow air directly on the factory installed hard drive. (Good thing) I have my drive in the bracket farthest from the fan witch also allows some space for the air to move around it up to the CPU area. My extra hard drive is mounted in the second 5-1/4" bay with brackets.

For the air flow on the CPU with the fan reversed, yes you can indeed feel the air moving. I still stand by the fact that is what the tunnel is for, to ensure air is being pulled across the CPU. As I said before, if the fan was supposed to be blowing into the case, the tunnel would not really be needed.


To heck with the other components, the CPU took precedent to staying cool.



I'm sorry, but that is just ignorant. There is a lot more in the case that generates heat than just the CPU. But lets go with that theory anyway. Where does the heat go now that the CPU is nice and cool? It builds up in the case and overheats everything else. "Hey my CPU is running great, too bad my hard drive is dead now because it overheated." If any one component should take precidence in the whole system it should be the hard drive. It contains your DATA. To lose that means many hours of recovery. A dead CPU can be replaced in minutes.

Robert_Wilkinso1

3 Posts

April 27th, 2005 03:00

Hey guys,

A word of advice, I'm stuck with my 4700 for a couple more years due to inability to have them give me a different system. If your not at home, make sure your puter ain't running. I was home luckily when mine did what it did. Mine actually caught fire, and it probably was due to the inadequate heat relief from inside the case. The powersupply shorted out, causing a fire on my motherboard on the CPU, and the graphics card. Did a nice number.. Let me know your emails if you wanna see pics.

Cheers,

Coz

jimi2

16 Posts

May 25th, 2005 00:00

I recently purchased a Dimension 4700 with 3.2Ghz processor.  I also found it very strange that the CPU Fan blows hot air into the case.
 
I downloaded a program called SpeedFan which reads the S.M.A.R.T. information from the Hard Drive and it indicated it was 69c/156f after 2 hours.  This was 14c/25f over the maximum operating temperature.  My previous computer's hard drive ran a steady 38c/100f.
 
The next day I removed the hard drive cage from the case and left the case cover off.  After 2 hours of use the hard drive temperature was 50c/122f.
 
Now today, I reversed the CPU fan, remounted the hard drive cage in the case and replaced the case cover.  After 2 hours of use, the hard drive temperature is 42c/107f.
 
I agree with firefox91, this seems to be the correct configuration.  The outside of the case now stays cool.  I can open the case and touch the CPU heatsink and it is barely warm.  Additionaly with this configuration, I can now feel air being drawn into the case from the lower front vent.
 
I would like to find a utility that will read the CPU temperature to further confirm my findings, but have note been successful.  Everything I have tried is unable to read the P4 thermal sensor. 
 
Just to note,  I did open a problem case with Dell Technical Support to ask them what the correct configuration of the CPU fan was.  So far they are refusing to answer any questions.  They are insisting on sending an onsite technician to replace the CPU heatsink and Fan. 
 

Grumper

271 Posts

May 25th, 2005 10:00

This is such an obivious solution that I can`t underestand why theses computers are put together this way, and this has been going on for years, I have a 4100 that came that way and I changed it.

The processors are basicly all Intel products. When you buy a retail Intel processor it`s covered for 3 years. Is there somthing we are missing here, heat + electronics = problems, Im sure Dell is aware or this situation and yet they keep on pumpimg them out.

Mistified

Robert_Wilkinso1

3 Posts

May 25th, 2005 12:00

I really feel this is grounds for total recall of these systems, I mean if I hadn't been home at the time my PC was burning up, it may have caught my house on fire. I had just moved in to the place I was at too and I hadn't had time to switch my renting insurance around. Oh what a mess that would have been. On top of this, I was promised by a customer service personel agent that for the troubled experienced I would be receiving a free graphics card upgrade, that to this day I have not gotten. I really feel dell is really pulling us customers around on a cart, knowing that with the cheap labour they use to build them is truly just making us all look like donkeys. I mean how much do you really think it takes to build one of these computers now a days. Has to be less then a 100 bucks. Think about it, at the time when quantity wasn't huge, the commodore 64 sold for 300 bucks. And it was mass produced but not the the extent of most of these new ones.

I really hope this system burns down my home, and when it does, I am going to sue Dell so bad, that I can retire.

natenmere

10 Posts

June 11th, 2005 21:00

Jimmi what do you mean by " you remounted the hard drive cage" and do you think it will be o.k. just to reverse the fan and do nothing else?  I am considering the fan behind the bezel, as that sounds very easy unobtrusive.  What do you think?
 
Also, is it possible that now the hard drive is cool because it is getting that fresh outside air across it, I am sure that is the case.  But is the top half of the case now trying to cool off the the hot air from the bottom half of the case, and creating a new situation where we have things overheating at the top of the case?   I hope not.  If you say the outside of the case is cooler than it before, then it must be cooler.

Message Edited by natenmere on 06-11-2005 05:54 PM

jimi2

16 Posts

June 12th, 2005 20:00

natenmere,

In my second experiment, before I reversed the fan, I removed the Hard Drive cage, and let it (with the Hard Drive in it) lay outside the case on the floor.   While this ran cooler, it did not run as cool as when I put it back in the case and reversed the fan and closed the cover.    I think this shows how important it is to have proper air flow through the case and over the Hard Drive.

If you are having similar problems with heat, I would suggest this is probably the first thing to try.  I just swung open the green duct, then lifted the black tab on the bottom of the fan shroud, then slid it down.  I then disconnected the fan wire from the motherboard so I could work on the fan.  I removed the fan assembly first from the shroud by "pinching" the rubber connectors and pushing them through the holes in the shroud.  I kept the fan assembly and shroud arranged in its previous configuration, (being careful to note the relationship between the far wires and the fan shroud.)  I then rotated the fan assembly 180degrees.  My fan wires were threaded through a slot in the fan assembly; I removed them and threaded them through the slot on the opposite side.  I then removed each of the rubber connectors from the fan assembly (carefully squeezing and pushing them through the hole) and then attached them to the hole on the opposite side of the fan assembly.  Once I did all four corners, I was able to push the fan assembly back into the fan shroud by aligning all the connectors with the corresponding holes and pushing each corner in until the connectors "snapped" in place.  Reinstalling the fan shroud in the case is a little tricky.  You need to make sure all 4 "legs" of the fan shroud are correctly aligned in their corresponding slots in the case.  You will be working against the pressure of the bottom tab on fan shroud.  This took me a couple of tries to get it right.  Once all 4 legs are in the appropriate slots, push the fan shroud up, and the bottom tab will snap back and the fan shroud will be locked in place.   Reconnect the fan wire connecter to the mother board, and swing close the green duct.

Yes, I agree with you that there is now cool air blowing over the hard drives first, then warmer air blowing over the CPU before being blown out of the case,  I don't think this is a problem. The CPU's operate so much hotter than the Hard Drive, that I don't think that a few degrees is significant.  Additionally my case cover has a perforated corner on the lower left edge that also allows air in.  This and the open vent at the lower back of the case (and the vent in front) are allowing plenty of air into the case.

I had downloaded another program called EVEREST Home edition, and it shows the DIMM temperature.  This showed 77c before and after I reversed the fan.  Unfortunately there is no way read the CPU sensor to determine its temperature.  All I have to say is that I have never had the system shut down due to the CPU Thermal Protection since I have reversed the fan.

Prior to reversing the fan, the entire top of my case was very warm (along with both sides also being warm).  After reversing the fan, only the top of the case immediately over the PSU is warm (but not as warm as before.) The rest of the top and sides are cool. (Maybe even cooler than when the computer is off. But I have no way to measure.)

When the fan was blowing hot air into the case, I think the case was acting as a thermal sink.  It was absorbing heat from the CPU and radiating it to every component inside the case.  With the fan blowing hot air out, I am now warming up the wall behind my computer, not the case and everything in it.

I would like to make one other point regarding air flow through a computer case.  If you are thinking about adding a second fan, sometimes it can make things worse.  You could end up with a "hot spot" because the fans are working against each other.  I had built my 3 previous computers, and they always ran cooler with the case covers on because the fan created low pressure in the case, drawing in cool air and exhausting hot air.  (I was in the processes of researching components for building my next PC when I came across the half off coupon offer.  I got the Dimension 4700 3.2Ghz, 512MB, 80GB, 16X DL DVD Burner, 2005FPW Monitor and 720 Printer for $830 (including 8% sales tax).  This was at least $200 less than if I built it myself.)

natenmere

10 Posts

June 12th, 2005 21:00

Jimi2,  I failed to mention that I was waiting to receive my 4700.  Well, I got it yesterday and the first thing I did was turn the fan around so it was blowing out.  Very easy as you mentioned.  I am now waiting to purchase a 6600 gt vid card which seems to be the card for my price range and the least amount of trouble with compatibility.  I'm sure the heat test will come then. 
Now about the fan you installed in the front.  I understand that you used zip ties to attach it.  Is it actually on the inside of the frame or between the bezel and the frame?  I have no floppy drive as well.  Did you say you used the power supply intended for the floppy?   Would I need to modify the electrical connection or will the fans connection fit into an existing power source?
I think you mentioned 80 MM fan.  I saw a number of 90 mm fans at newegg( I didn;t really look very hard).  They have like 1000 fans to choose from.  Will the 90 mm fit?  I also have the holes on one side near the bottom.  I am thinking just turning the fan will be fine but another fan is very easy and cheap to do.  Thanks for the feedback.
-Nate

jimi2

16 Posts

June 14th, 2005 23:00

natenmere,
 
I have not added a second fan,  that was firefox91 (2-26-2005 11:31 pm; 80mm fan with zip ties.)
 
I was also considering this, but the power switch and led extensions on the front case cover would seem to interfere with mounting on the outside.   I have seen at MicroCenter a 90mm fan that mounts in a Hard Drive bay, but since I have added a 2nd Hard Drive, this is no longer an option for me.
 
Regarding power, the fans I looked at used 5v from an IDE Hard Drive Connection.  There are power splitter plugs available if you dont have enough available connections.
 
Right now, I am not sure a second fan is necessary for me (on board video suits my needs).  I do not like the vertical mounting of the Hard Drives.  With the second Drive, I think it is blocking some of the air flow from the front of the case.  I am trying to think of ways to mount the Hard Drives horizontally with more space between the drives.  (Maybe an old removeable Hard Drive cage from a scrap PC mounted to the bottom of the case, I have not done any measuring yet, may not clear the Motherboard.) 

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