How much is too much - thermal paste

Too much is harmless, just a bit messy.
Wont damage your pc.

Looks like - way too little. The paste has to cover most of the die.

Basically you have a CPU, Transistor, etc.... Some electronic device designed with a heat pad. It is designed so all the heat goes to this metal plate. In the case of a CPU it's the top die. You slap a heatsink on it and it takes that heat away. You want the surface of the heatsink to touch the entire surface of the CPU's heat plate so it works better. Imagine a curved heat plate and the heatsink was rocking on top of it. Not much heat would transfer into the heatsink.

In the case of PC heatsinks and CPUs, they are ground so friggin good that they are practically flat. I'm talking microscopic laser manufacturing here. You can read reviews from sites like frostytech and they review how flat and well machined the heatsinks are. You could take a good CPU heatsink, slap it right on the CPU, and you wouldn't have much problem. The heatsink is made of aluminium and copper and it is a very good conductor of heat and does a good job.

Now imagine taking a material and slapping it in between the heatsink and the CPU. It acts as a barrier and stops the heat from transferring from the CPU to the heatsink. The heat now has to transfer to this barrier then to the heatsink. Thermal compound acts as this barrier. So in essence thermal compound is bad. But imagine the curved top of the badly manufactured CPU. And the bad quality heatsink that is also curved. They don't sit flat together so you get little contact and no heat transfer. The thermal compound will fill this air space and help transfer more heat.

So the answer is. With a perfectly flat CPU and Heatsink, thermal compound is bad. Without a perfect heatsink and CPU, thermal compound is good, but just enough to fill the voids, not so much that is acts as a barrier. Thermal compound is rated with it's thermal properties such as how well it can transfer heat in watts/hr or something like that. It is not as good a heat conductor as having aluminum on aluminum, but it's better than not having the heatsink touch the cpu and there being an air space. It is also designed to not conduct electricity so if you have spillage it won't short your electronics.

Like I already mentioned. Heatsinks and CPUs are very well designed. So you need very little compound. Having no compound is usually better than having too much and a big mess. But having some is better than none because compounds are very high performing now and transfer heat pretty good, so they act less like a barrier. The rule of thumb is to put a dab on the CPU the size of a pea or something. Take something flat like a piece of paper or plastic like a credit card. Spread it out into a very thin layer. Add more or remove the excess with the scraper. You want your layer very thin you can practically see the metal through the compound. Many people use a razor blade to clean the old stuff off and spread the new stuff. Be careful not to scratch the metal this way or that creates the dreaded air space that must be filled by compound.

Now with the compound applied you install the CPU. Then install and tighten the heatsink. The pressure of the tightened heatsink will smooch out the compound and spread it around. Remove the heatsink and look at the bottom of it. You should have a perfect square of compound on it meaning you had good contact from the heatsink. I've seen people install a heatsink wrong and when you check the bottom of the heatsink it didn't show signs of compound on the bottom being flattened out. This is a good check to make sure the heatsink is making good contact. You are good to go.

Once the heatsink has been installed and removed the compound will be so thin you see the etal right through it. The bottom of the heatsink will be spotted only showing compound where micro voids where. It's almost like there is practically no compound at all. Remember these things are manufactured super flat. If you use too little compound not a big deal. If you use too much usually not a big deal since there is a lot of pressure from the heatsink so it'll force the compound out, and the compound is so viscous that it easily oozes out. Use way too much and it'll make more of a mess than anything.

A good case with good airflow will have a bigger impact than the thermal compound quality and method of installation. A good case can have a 5 degree effect while good vs bad compound may only be a 1 degree difference on the CPU. Your room ambient temperature also has a major impact on the CPU temperature so you want air conditioning in the hot summer. Also the design of the heatsink is of bigger importance than the compound itself. Get a good heatsink and it can make a 10 degree+ difference. Don't worry too much about the compound, just understand it's true purpose.

Hope this clears things up a bit. Thermal compound is mystery to most beginner computer builders who don't know electronics. They assume the compound is to transfer the heat and are scared if they don't use it. It's only there to fill the air space, if there is one, and heatsink directly on CPU will transfer heat much better.

Too much paste won't damage your PC, but it will make the CPU run a lot hotter.

The role of thermal paste is to fill in microscopic air gaps between the CPU and heat sink (because their surfaces aren't perfectly flat nor smooth). Paste is about two orders of magnitude more effective than air at transferring heat. But likewise, metal-on-metal contact is about two orders of magnitude more effective than paste at transferring heat. So you want enough paste to fill in the air gaps, but not so much paste that you're reducing the metal-on-metal contact area.

If you look at tests done with no paste:

https://www.hardwaresecrets.com/thermal-compound-roundup-january-2012/5/

The temperature differential between CPU and air was 62 C with no paste, vs about 35 C with paste. The rate of heat transfer is proportional to the temperature differential. So assuming the CPU was generating the same amount of heat (Q) with and without paste, in the no-paste case you get a heat transfer coefficient of:

Q = c_nopaste * 62 C
c_nopaste = Q / 62 C
c_nopaste = 0.01613*Q

Heat transfer works like electrical current flow, except the equations for parallel vs series resistance are switched. So for the thermal paste case, you have parallel flows between metal-on-metal (no-paste), and through the paste. And the resulting equation is:

Q = c_nopaste*35 C + c_paste*35 C

Combine with the value of c_nopaste we got earlier and you get:

Q = Q *35 C / 62 C + c_paste*35C
c_paste = (Q - Q*35/62) / 35 C
c_paste = Q*(27/62) / 35 C
c_paste = 0.01244*Q

So the majority of the heat (56%) is being transferred via metal-on-metal contact. The paste only transfers 44% of the heat despite accounting for a much larger percentage of the contact surface area (which I left out in the above equations to simplify the calculation).

In other words, if you use too much paste, you're going to eliminate 56% of the heat transfer via metal-on-metal contact, and replace it with a tiny amount of heat transfer via the paste (about 0.56% since paste is about two orders of magnitude worse at conducting heat than metal-on-metal). And your CPU can actually end up running hotter than it would without any paste. (In reality, the compression clip on the heatsink will squeeze most of the paste out and still generate some metal-on-metal contact. The role of the clip is to squash the microscopic peaks in the metal surfaces, to increase the metal contact surface area. This can be impeded if too much paste is in the way.)

You only need about a half-pea to a pea-sized dollop of paste. The amount paste manufacturers recommend is generally way too much (so they can sell you more paste). I squish the heatsink down, then twist and slide it around the spread out the paste. When I feel metal starting to grind on metal, I know I've squeezed out all the excess paste, and I clip or screw the heatsink down. Remember, the role of the paste is to fill in microscopic air gaps. You do not want the paste slathered on like a layer of mayonnaise on a sandwich. You want just enough paste to fill those tiny gaps; any more will reduce the amount of metal-on-metal contact area and result in higher temps.

This is the best answer by far: https://www.youtube.com/watch?v=r2MEAnZ3swQ

In the end the conclusion is that too much is not an issue at all, it does not make any difference. The only bad thing is too little paste.

The only real issue with too much paste is that if it is conductive and some of it ends up getting on the motherboard - you may short stuff, which is bad. But thermal properties-wise - no issue with too much paste.

This test proves some points. The reason less paste fails is because the heatsink isn't perfectly microscopically flat and contacting the CPU on 100% of it's plate. Too much paste or any design of applying it doesn't make a difference because there is so much pressure on the mounting of the heatsink that it just smashes the paste into an even spread. Too much and it just oozes out and makes a mess.

The part of it being conductive and shorting the motherboard is BS. I don't think there are any thermal compounds being sold for or given with CPU heatsinks that are electrically conductive. They are thermally conductive but not electrically.

The best method is to just spread small layer over the CPU die to get 100% coverage and install the heatsink. Just don't use so much that it oozes out. Just a very thin layer. Any bit that oozes out will create a tiny border around the CPU but no mess that leaks out. By putting a dot and installing the heatsink it oozes out into a circle but you don't get 100% coverage over the CPU. The reason his results were the same is because he had metal on metal contact around the circle of compound. A thin layer spread out gives 100% coverage and the best chance of the best results.

But in the end he gets the same results which shows that my original comment stands. Compound doesn't makes much of a difference. Put it on, use it, but don't worry about it. Room temperature and fan air flow, and dust make the biggest differences.

I couldnt agree 100% of the time.

In a lot of cases, too much paste will cause higher temps due to the past trapping the heat in around the edges, to explain it simply.

To the thread creator, it looks like theres minimal paste. I would clean, and reapply with a little more. Most of the dye should be covered.