Thermalright SI-128 SE Heatsink
Author: Zahn Funk
Editor: Shawn Knight
Date: 11-13-2007
Provided by: Thermalright
Discuss: View Comments
Testing / Conclusion

I'll be comparing the performance of the Thermalright SI-128SE to the stock AMD heatsink at stock speeds and various levels of overclock. Stock coolers are usually adequate at keeping temps under control at stock speed and voltage, however it's when increasing speed and especially voltage that much higher demands are placed on CPU cooling. To monitor CPU temperature I used a utility called CoreTemp. Rather than rely on motherboard sensors which can vary wildly in their accuracy, the CoreTemp program reads temps directly from the Digital Thermal Sensor embedded in the core of the CPU by the manufacturer. Since my 5200+ X2 Windsor has two cores, two temperatures are reported. I logged the readings over a period of time, then averaged each core individually and used the median value for reporting. To generate load temps I ran two instances of Folding@Home, bringing each core to 100% utilization.

As you can see, the stock AMD cooler is quite capable of keeping things under control at stock speeds. However as voltage and speed increased, temperatures quickly climbed out of control. By the time the CPU exceeded a 20% overclock and .3v over default, the cooler was no longer able to keep things stable and the system crashed at 65 C.

Next up, the SI-128SE.

Wow! As you can see, the Thermalright SI-128SE leaps out of the gate and quickly puts nearly a 10 C load temp lead on the AMD cooler, even at stock speed and voltage! The gap only continues to widen as frequency and volts increase. At a 20% overclock and .2v over stock the load temp difference is a whopping 20 C and at .3v over it would likely have been even more had the system not crashed with the AMD heatsink in place. In contrast, the system was perfectly stable and happy at a 25% overclock with the SI-128SE keeping load temps under 50 C. In fact, it probably could have gone even higher if the inclination to use more voltage was there.


Thermalright is well-known for their excellent products and the SI-128SE is no exception. When coupled with just an average 120mm case fan the cooling ability of this heatsink is outstanding and runs moderately quiet to boot! Quite probably its performance would be nearly equally as impressive with any "silent" low-speed fan, although I did not have any to test with. With past coolers, using higher CFM fans did not substantially lower temps much further, however certainly there is some extra potential there for those that don't mind the noise.

When it comes to quality, Thermalright again sets the bar for other companies to follow. Although there was a slight clearance problem with the support bars on our SI-128SE as received, simply tapping them a bit farther into the base/fins resolved it. Installation otherwise went very smoothly, as long as you don't mind too greatly having to remove the motherboard in order to install the proprietary backing plate. This is fairly common for a cooler of this size however, and I don't feel it should be much of an issue for most users.

Price-wise the SI-128SE goes for right around $50.00, which may seem like a lot especially considering you don't get a fan with that. But in reality this is about average for a cooler of this magnitude, and I don't think this should raise any eyebrows among overclockers and computer enthusiasts. For the quality and performance you get, the Thermalright SI-128SE is truly a great value.

Thanks to Thermalright for providing the SI-128SE for review.

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