Installing a cooler on a processor
Background to the experiment: CPU cooling (LGA775 socket) was provided by the CNPS7700-AICu cooling system. Intel Pentium D930 processor, was purchased in 2005. At that time, quite powerful and expensive. Therefore, I did not save on cooling. Bought a Zalman CNPS7700-AICu. For four years he regularly performed the task assigned to him. There are no complaints about cooling the processor now, but it has become pretty noisy.
Therefore, I decided to send the old man to retire and started repairs. It is repair, because replacement is laziness and squandering, at least in this situation. In place of the noisy fan, I decided to put Floston, because the noise from it is less than from the dead, but it costs a penny in comparison with its predecessor.
Since the cooling system itself is very high quality, it was decided to leave the radiator. The fan decided to build Floston. Since the shape of the petals of the old Zalman and Floston was different, part of the body of the latter had to be removed so that the side blades of the radiator were blown. The result is such a design:
refurbished Zalman cooler
I installed the radiator in place, started the computer and after 10 minutes received an alarm – overheating. CPU temperature exceeded 60 degrees. The first thing I thought about: Bad contact between the processor and the heatsink due to the installation according to the scheme of crooked hands. Dismantled, assembled, checked. Same. Overheating, apparently, happened due to the fact that when I dismantled the radiator, I replaced the thermal grease and applied it with a thinner layer and the surfaces of the radiator and processor are now not completely in contact. I had to identify and correct the cause of poor contact.
When installing a radiator (even if it is at least twice new and expensive), it is very important to ensure that the surface contact is maximum. Neither the price nor the company guarantee this today, unfortunately. Those who think that thermal grease will fix everything are mistaken. Thermal grease is used to fill small voids in order to improve heat transfer. This is an assistant, but not the main employee. Over time, thermal grease dries, hardens and loses its thermal conductivity, so the less it is, the better!
I have repeatedly come across the fact that even expensive cooling systems do not always have a perfectly flat radiator surface. To this may be added a slightly deformed (bent due to uneven pressure by the clamping mechanism) surface of the processor itself. In general, we are talking about a maximum about some fractions of a millimeter, but this circumstance can provide a difference of at least 7-10 degrees, believe me! The case of this article is just from this series.
How to determine the quality of contact? After installing the processor, you need to apply a thin layer of thermal paste. Since the subtle concept is relative, I’ll clarify. Apply a small drop of thermal paste (with buckwheat grain size) to the tip of your finger, then smear it on the surface of the processor in a circular motion. Hands should be clean, oil free. It should be something like this.
thermal paste application
After that, you need to attach (no need to press) the heatsink to the processor and slightly (several degrees) turn left-right.
After that, you should see what trace the thermal grease left. In my case, I got two thin stripes around the edges. This meant that the surface of the radiator was deformed with time and had a depression in the center. Therefore, it was necessary to straighten it back. To do this, I needed a large and medium sandpaper and a flat bar. I used a radiator from an old computer as a bar. We remove traces of thermal paste (best of all, it is cleaned in a circular motion with toilet paper) and take up sandpaper.
To determine the scale of the tragedy, you need to process the radiator with a large emery cloth so that it leaves scratches, then smaller ones. Fine sandpaper will smooth out large scratches, they will remain only in the cavity. If you examine the surface of the radiator to the light at an angle, it will be very clearly visible hollows (bumps). The hollow in the center is clearly visible in the photo.
uneven platform surface
The radiator is processed until large scratches disappear. You do not need to press, otherwise there is a risk of sharpening the edges, which will lead to the opposite effect – a bulge is formed. When the scratches disappear, you can polish the radiator with fine sandpaper (null) or an abrasive (ordinary soda will do). Then, repeat the operation of applying the heatsink to the processor.
In my case, the fault was all the time, the radiator was subjected to heating cycles for 4 years. It played a role. And replacing the thermal grease when dismantling the radiator just made the problem worse. But, as noted above, now you can easily buy a new radiator with a non-ideal surface. So the radiator installation procedure must always be controlled!
In general, I sent the radiator twice for revision, because the result did not seem to me satisfactory. Photo with intermediate results:
Polishing the cooler landing pad