AMD Wraith Prism Cooler

The AMD Wriath Prism cooler is a really nice stock cooler, but it has one significant drawback.

AMD Wraith Prism Cooler (bottom)

You can see from the picture the outline left by the Ryzen CPU. You can also see all the uneven grooves in the cooler surface where the heat pipe itself is left to be the interface to the CPU. This unevenness allows for variation in the gap that heat sink compound has to fill. This leads to an uneven heat distribution and lowers the efficiency of the cooler.

Noctua NH-D15 (bottom)

Notice the smooth high polish surface of the Noctua NH-D15. This finish allows for a small amount of heat sink compound and a higher degree of surface mating area with the CPU. This leads to a higher thermal efficiency. Most, if not all, aftermarket coolers will have this high degree of finish.

In testing, the Wraith Prism cooler did indeed hold the CPU to 85C at full load when running Prime95. In general computing/gaming the stock Wraith Prism cooler is a good cooler. With a touch more work, it could have been even better.

Cooling Upgrade

Replaced the stock Ryzen Wraith Prism CPU cooler with the Noctua NH-D15. The Wraith is a nice stock cooler, but under load it tends to be noisy.

Installed NH-D15 next to the replaced Wraith Prism

As you can see there is a substantial difference in cooling area of the NH-D15 over the Wraith. The bigger fan size means less noise for sufficient air flow too keep the processor cool under load.

Installed In The Case

Because of the height of the RAM, the front fan had to be mounted higher. Luckily the Lian-Li case had enough clearance. Barely.


DIY – Router Repair

My faithful RT-N66U router died last night. Luckily I was only using it as an access point and wifi was all that was affected. The unit’s power was completely out. I feared that the wall adapter had gone bad. I noticed that the push-on/push-off power button was in the out/off position (see below).

RT-N66U Back View

Upon pressing the power button in the power would come on, but the power button would no longer lock into the in/on position. A wonderful piece of technology was at the mercy of one of its absolutely cheapest parts.

To repair it I decided to open it up and bypass the power switch altogether (I never used it in the first place). I’m sorry, I didn’t think to take any pictures, but I will endeavor to describe my process in the repair.

The RT-N66U has several screws on the bottom holding the top cover in place. Once removed you have to gently pry the top cover off. There are tabs around the front and sides holding the cover on.

How to open the RT-N66U

With the cover off, the board slips right out of position and is easily removed. To get to the underside of the power switch the metal RF shield on the bottom has to be removed. After removing the screws holding it, it pulls away without issue.

RT-N66U PCB Removed
RT-N66U PCB Bottom With Shield Removed

The power switch has 4 soldered pins. From the above picture, the top-most and bottom-most pins are attached to the metal frame surrounding the switch. The 3 center pins control the switch contacts. Using a continuity meter, I found that when the switch is on the out/off position it connects the top pin with the center pin and that this connection is to the ground leg of the power connector. When the switch is in its in/on position the center and bottom pin are connected. The bottom pin is connected to the positive leg of the power connector. This configuration means that we cannot simply bridge across the switch without removing the switch as the power would then be shorted.

Once the switch was removed it became a trivial matter of using a small piece of jumper wire between the center pin and the bottom pin to create and always-on connection. Now my faithful access point is back in action for hopefully many more years to come.