Mega Shadow – Lapped or Not?

I’ve been asked by Nick at CrazyPC.com to test the Prolimatech Mega Shadow heatsink. The purpose of the test is to see if lapping the heatsink will give any performance improvement. Since I already have a Megahalems in one of my secondary rigs, I found the idea interesting. The testing procedure will be simple. For each step, I will do three mounts and run the test app three times, then average the results. The thermal interface material application method will be a pea sized drop in the middle.

The test rig will be the following:

• Intel Xeon W3580 CPU
• EVGA E762 4-way Classified
• 3 x 2Ghz G-Skill Perfect Storm
• 1 Sapphire Radeon HD 5870
• Silverstone Strider 1500W PSU
• Navig Bench Station
• Prolimatech Mega Shadow Heatsink

The setup will be as follows:

• CPU frequency 4014 MHz
• Multi 25x
• Bclk 161
• Vcore 1.350
• Ram ratio 2:12
• Everything else on auto.
• The TIM will be the one provided with the unit.
• Ambient temp is 75°F (23.9°C).

First let’s take a look at the victim:

Let’s start with the non-lapped heatsink results.

When looking at the finish and smoothness of the unit, I thought it was almost a sin to lap it! But for the sake of testing, I had to! As stated before, I did three mounts and three Prime95 Small FFT runs for 15 minutes each.

Now let’s move to the lapping part. To be honest, that was a real workout! The kit CrazyPC sent me consisted of 5 sheets of sand paper – 120, 220, 400, 800 and 1000 grits. It took me about five hours to get the thing done. As a side note, I didn’t like the finish/smoothness after the 1000 grits session, so a trip to AutoZone got me some 1500 grit.

Now the lapped heatsink results.

What a disappointment – no gain! I made sure no change in ambient temp, was really careful when mounting the unit, but numbers were speaking to me. So, to make sure that the contact was good, I did some pressure modding. This consisted of putting some washers between the mounting bracket and the base. Let’s see if it worked.

As you can see, no improvement!

The Mega Shadow is a great heatsink right out of the box, the mounting system is really well done, probably one of the easiest to work with, making multiple mounts a breeze. Prolimatech does not recommend lapping the heatsink:

“Prolimatech does not condone any type of lapping done to the CPU or to heatsink base. Every Prolimatech’s heatsink base is designed on a pin-point scale of how the base is to be flat and/or curved where it’s needed to be. We have programed our machines to machine the surface in a very calculated way. Any after-manufacture lapping or modding done to the base will alter the design, hence negating its performance factor as well as its warranty.”

Now we know why. So for future users, don’t spend the time and effort into lapping this unit, you won’t see any gain by doing so.

I would like to thank Nick from CrazyPC.com for providing the unit and the lapping kit. The Prolimatech Mega Shadow heatsink is available at CrazyPC.com for $77.99. The premium lapping kit is available for $10.99; although I do not recommend it for this heatsink, it might be a good option for other cooling devices. For reference, this product is out of stock and priced higher ($89.99) at Newegg.

–icebob