Leaking heat pipe?

I've noticed that over time, my CPU temp has been gradually increasing, regardless of undervolting, cleaning the heatsink out and all the rest. For a comparison, I used to idle at 35-38 with no undervolt, I now idle at about 55 with undervolting. However, the GPU temps seem to have stayed pretty much the same taking into account the stubborn dust that you can never quite off (used to be round 45-48 with MX-3, now it's at 50-53).

Given that the GPU seems to be pretty much where it has always been and that both their heat pipes connect to the same cooling vanes, this would lead me to believe that the CPU heat pipe is sttarting to die. When I gutted this whole thing, at one point I ended up running it without the base plate on and the CPU heatpipe seemed very hot directly overhead but not very hot further down, suggesting it's not transfering heat properly. I do remember that I accidently bent one of the heat pipes a little by accident too.

Anyway, back onto the main subject, is it actually an issue that has happened before and is possible or are the chances so remote that I may as well just rule it out as a possibility. I'm probably gonna end up getting a new heatsink eventually but if this one really is dieing and not just full of stubborn dust then that's more of a motivating factor.

 

I've heard of bent and then leaked heat pipes. But losing the heat conductivity is not a slow process, it happens suddenly (within seconds or minutes).
I could imagine that this happened to your bent heat pipe while the other one is still ok. In this case there shouldn't be any further regression in the efficiency of your cooling system.

 

Perhaps a new heatsink cooling system is in order? I see a whole bunch on Ebay for ~50 bucks. Are you still in warranty? Adunno if you can order it through XPS as a CRU.

 

You can test this. Remove the cooler. Boil some water. Hold one end of the heatpipe and dip the other end into the boiling water (about 1/3-1/2 of the length of heatpipe). The end you are holding should become VERY hot VERY quickly. If not, then it isn't working.

 

Have you considered decrapifying or reinstalling your OS? Heatsink efficiency is only half of the cooling equation. If your computer is running background processes 24/7, your temps will rise simply as a matter of a greater workload. A simple way to test this (simpler than wiping, anyway) would be to install the OS to a spare hard drive, another partition, or to try using a LiveCD/LiveUSB to test the computer.

Not that this will be a major factor, just a possibility to try before dropping $ on a heatsink. They're not exactly dollar-store parts.

 

While I do think that CPU load does take a small part in the heat I'm experiencing (for example I run slightly cooler in a new win7 partition I made), it doesn't seem to make that much difference, I also haven't played about with my other installation of windows for long enough to get a real idea, it might have just been that I only had it on for five minutes and so it had very little time to heat up.

At its prime, just after I undervolted and applied MX-3, I used to load out at about 65, now I can usually hit 75. Because these are load temps, since the system is running flat out anyway then the OS shouldn't make any difference.

Also, if I ever take off the heatsink again, I will try dipping it in water. Another possibility which I thought of, is that instead of the coolant leaking I could have screwed over the wick inside. Because of the importance and small size of laptop cooling, they'll have almost certainly used the best wick type available (sintered metal). I can quite reasonably see this cracking off if it were in any way disturbed though, since it's probably got pretty much the same structure as a teracotta pot. Since I bent the heat pipe a little by accident, I think it may be possible that some of the wick has cracked off, reducing the heat pipes effectiveness.

 

Yeah I noticed that when doing my GPU heatsink over and over (with some bending for larger cards). I got a fresh one and was returned to full cooling performance.

 

I also remember shaking it and hearing a faint rattling noise, I just assumed that it was the coolant but now I think about it more it could have been a chunk of the wick bouncing round inside.

Note to self: be more careful with heat pipes in future

 

Indeed, heatpipes rely on the pressure and heat change to get the right liquid/vapor equilibrium to work like a compressor/condensor setup. Change the volume and shape of the pipe and you can mess it up.

 

That is a possibility. The wick basically makes the heatpipe work in any orientation, not just with heat on the bottom (pipe vertical). In a notebook the pipe would be horizontal.

 

I bent a heatpipe and then I got it extremely hot with a blowtorch. The whole thing expanded in diameter, so it went from flat to round. I think I can assume there is still some liquid in the pipe here.

I tried it on a another heatpipe which definitely didn't work. It was more bent up.
Tho if you try this yourself, don't give up too easily. Hold it with a pair of pliers and take a lot of time.

Oh really?
And because they are Dell, there is no chance they would have used something else to cut costs?
I have heard that water filled heatsinks are particularly effective without a wick, although they depend on the notebook laying flat to work.

Some heatpipes are gravity driven, so this might not work. See above.

 

It will work. Gravity causes the liquid to pool at the bottom, which is the end that dips into the hot water.

 

Almost any heatpipe will have a wick, if it didn't then as soon as you move it to anything off horizontal then the coolant woud pile up at the cool end and the whole thing would be useless. Although dell are known for cutting corners, there are just some corners that you can't cut. Also, I've run this computer upside down, sideways etc. and it's always performed pretty much the same.

As for them not using sintered metal, it is possible that they could have used a braided wick, but given the length of it I doubt they'd use the cheapo grooves. Heatsink wick material makes little difference to the price overall, and they knew the machine had problems with heat from the start so it's pretty safe to assume that it's got something better than grooved metal for a wick.