Noctua NC-U6 – in practise

For a few months my Asus P5N-E SLI board had been suffering from two particular “problems”:

  1. CPU (E6600) core temperatures were significantly higher than what others were reporting.
  2. Overall system temperature higher than it should be (requiring me to keep my A/C on all day!); I use an Antec P182 case, which received incredible praise for dampening noise and providing effective cooling at the same time.

To try and alleviate #1, I invested in a Nexus LXM-8200 CPU HSF, naturally assuming the issue was too much heat being output from the processor or stock Intel HSF itself (which is apparently an atrocious HSF). After installing the LXM-8200, I found my core temperatures had dropped 2-3 degrees Celsius during idle time, which was nothing impressive. Under load, the LXM-8200 decreased temperatures by about 7-8C, which was impressive. I still use the LXM-8200, by the way. But the system temperature didn’t go down at all. Hmm…

I knew that the nVidia 650i SLI northbridge and southbridge were renowned for “running hot”, but I couldn’t find any reviews on the web which provided comparative numbers. It seems every review site skips the most important things, leaving it up to grammatically-impaired forum users to discuss such issues — not cool (pun intended). I needed a way to determine what the source of heat was, so I bought an Extech IR201 infra-red thermometer to help track down the source. A few days later, the Extech arrived, and it took me a matter of minutes to determine the culprit:

Lo and behold, the top of the stock Asus HSF read anywhere between 60-65C depending on where I focused the laser (the closer to the motherboard I got, the hotter the temperature). There’s no HSF on the southbridge, which read a consistent 60C. Hot hot hot! I quickly concluded that Asus had placed their HSF too close to the main CPU, and that the amount of heat it was giving off was probably influencing my CPU core temperatures.

Hence my investment in the Noctua NC-U6.

The first thing I noticed about the NC-U6 was the price. Almost US$30 — not cheap for something as “simple” as a chipset cooler. I purchased mine from, and it took about a week for the product to arrive. It sat on my desk for 4-5 days before I decided I wanted to give it a try. I intentionally removed the P5N-E SLI from the case, as I wanted to make absolutely sure the NC-U6 would fit on the northbridge with the LXM-8200 mounted.

After a few minutes of futzing around with the arm locations, lining up the mounting push-pins with mounting holes, and triple-checking the need for the square foam used to “level” the HSF on the chipset, I concluded that the NC-U6 would work just fine with the LXM-8200, leaving about 3/4″ space between each (well within reason). I applied Arctic Silver Ceramique to the NB and did my best to install the HSF (I use Ceramique on things like chipsets, and AS5 on actual processors). Here are some things I noted about the installation process, and the installation results:

  1. The square-shaped foam which you place on the chipset has to cover some resistors which stick up from the NB PCB itself. I had concerns over this, worrying that it might cause the HSF to sit unevenly on the die… but without it, I risked damaging the surrounding NB PCB area (thus those resistors)! I decided to use the foam as per Noctua’s installation instructions.
  2. The NC-U6 can easily “wobble” from side-to-side when mounted properly, even with the square-shaped foam “level” in place. This is one of the biggest concerns I have with using this chipset cooler on the 650i SLI NB. Noctua should have included a couple different foam squares (preferably one which covered more surface area!), especially for the price.
  3. It can also rotate while mounted (this is intentional, as to give you 120-degrees of rotational room in the case your video card, RAM, or CPU HSF get in the way); however, by tightening the middle screw, you can ensure the HSF won’t rotate. Leave the screw a tiny bit loose while doing the install, position the HSF however you need, then tighten the middle screw down.
  4. Due to Asus mounting the 650i SLI NB at an odd angle (positioned like a diamond (45-degrees rotated), rather than a square/rectangle), and the location of the arms on the NC-U6, the base of the NC-U6 ends up being positioned 45-degrees opposite to the NB die. This is hard to explain with words, but I don’t have a picture to show. :-) If you try the installation, you’ll see what I mean. Anyways, it’s not something to worry about, but it likely plays a big role in regards to Item #2 above.
  5. The weight of the NC-U6 is acceptable, and even with Item #2 in mind, the HSF isn’t heavy enough to cause it to “pop off” the board once a motherboard is mounted in a case (read: vertically). In English: don’t worry about the weight of the HSF. :-)
  6. I had no issues with clearance when it came to my video card. If your video card has a very large HSF on the back side of the card, you may run into problems.

I also took the liberty of re-installing my LXM-8200 while the motherboard was out of the case, as I had some issues with the plastic expanders not feeling like they were all the way through the motherboard. As I briefly mentioned above, I used Arctic Silver 5 between the LXM-8200 and the E6600. After reinstalling everything in the case, I booted up Windows and fired up RMClock while simultaneously grabbing the Extech thermometer. After 15 minutes, I was absolutely stunned at the difference the NC-U6 made. Here’s the before-and-after chart, with readings from the NB taken via the Extech thermometer (“top” means the highest point on the HSF, and “base” means as close to the die or motherboard as I could get):

Before NC-U6 After NC-U6
CPU (idle) 40-46C 33-37C
CPU (load) 56-60C 47-52C
650i NB 60C (top), 65C (base) 30C (top), 40C (base)

Needless to say, I am a very happy camper, and the results speak for themselves. And remember, that’s using Arctic Silver Ceramique, not AS5. What all of this proves is that the stock NB cooler that Asus includes with the P5N-E SLI is responsible for increased temperatures around the system CPU.

If the 650i SLI was still the “latest and greatest chipset”, I’d recommend Asus issue replacement HSFs to any customers who complained. Though, Asus has a tendency to just throw a high-speed (read: loud) fans on chipsets to alleviate cooling problems. The NC-U6, lightweight and sporting two heat pipes, proves a fan isn’t necessary.

Other people’s reviews: