Before I start, I'd like to thank the folks at Enerdyne for sending out a kit of Indigo Xtreme for this review. It's been a pleasure dealing with them as I give them feedback and toss questions their way.

Intro

In this review, I will be testing five TIMs and comparing how they perform compared to each other and how they behave over a twelve hour load. The five TIMs being tested are: Arctic Cooling MX-2, Arctic Silver 5, IC Diamond, Indigo Xtreme, and Shin-Etsu X23-7783D. While not a conclusive review of every product on the market, it includes three of the most popular TIMs: MX-2, AS5, and ICD, as well as the newcomer and a wildcard, Indigo Xtreme and the Shin-Etsu, respectively.

The Indigo Xtreme TIM is, frankly, a totally different TIM compared to what computer enthusiasts are accustomed to. It's not a ceramic paste, it's not a metallic paste, it's not a metallic paint, it's not a liquid metal, it's not a metal pad, it's....something very different. The makers of Indigo Xtreme say it best: "Indigo Xtreme™ is a self-contained and sealed structure, deploying a Phase Change Metallic Alloy (PCMA) which reflows and fills surface asperities on the CPU lid and heat sink. The resultant interfacial layer is void-free and robust, with low thermal contact and bulk resistance." In Layman's terms, it's a plastic card-like outer frame with a partial ring of metal that, once heated and allowed to reflow between the IHS and the cooler, forms a thin layer of metal perfectly adapted to the two surfaces. It's a high-tech TIM.

Arctic Silver 5 is an old-timer in this group. It was a new TIM all the way back in 2003 yet it's very competitive with today's "new generation" of TIMs and is still incredibly popular. It has evolved into the TIM to which every other TIM manufacturer compares their products, as big a compliment as any. Despite being an old product, Arctic Silver provides updated application instructions for even Intel's newest processor, Core i7, and promises to perform well.

Arctic Cooling MX-2 is, arguably, the most popular TIM in the enthusiast community. It's known for exceptionally easy and consistent installation, great performance, non-conductive and non-capacitive qualities, and for being non-curing. It's also become popular in the testing community as it's readily available in large, 30g syringes for a reasonable price.

IC Diamond is Innovation Cooling's first product on the market and it's made a big splash in the enthusiast community. They entered the market with a bang, using buzz marketing and seeding hundreds of users with their TIM for free and having the users report performance in return. It is a thick, diamond-based TIM promising noticeable performance increases over the likes of MX-2 and AS5. At the time of writiing this review, Innovation Cooling reports that "336 Independent users in ten different forums used their own PCs to test the difference between IC Diamond and other thermal compounds. This independent testing shows an average performance gain of 3.65 ºC over other thermal compounds (Tests are still in process)."

Shin-Etsu X23-7783D is Shin-Etsu's least thermally resistive TIM and their easiest to work with, according to their data. Shin-Etsu doesn't market to enthusiasts, nor do many people know about their specific offerings, but many enthusiasts do associate Shin-Etsu with good TIM. To be honest, as the world's largest supplier of semiconductor materials, the enthusiast community's interest in TIM is probably way off their radar.

Thermal Testing Methodology/Specification

Methodology

My TIM tests are a derivative of my waterblock tests. I use Dallas One Wire DS18B20 temperature probes at various points through my watercooling loop and at the air intake to measure temperatures, I use the same pump and block on every test, and use good testing practice by performing 5 mounts (when possible). Where applicable, I follow manufacturer's installation procedures to the letter. For my TIM tests, I'll be plotting temperature vs. time, in the form of a 60 minute moving average (or less for the first hour of data). Despite the 1C resolution of the Intel DTS sensors, these tests can be considered statistically highly precise due to the immense amount of data acquired from polling every sensor/probe/meter every second over the course of 12 hours. A moving average is used to smooth out the noise associated with this kind of measurement and to maintain a very high precision of information. A typical TIM test, in raw .CSV outputs, will include roughly 6,500,000 data points per TIM. In the end, all that data can be processed down to one value: what temperature the TIM provides.

I will be examining two specific components of TIM performance: how long it takes to cure (if within the 12 hour testing time) and what kind of temperatures an end-user can expect.

Specification

• The processor I'm using for this test is my C0/C1 i7 920. I'm running it at 21x200 (4200MHz) at 1.49V loaded on a Gigabyte EX58-UD5. It is unlapped. I'm running 2GB of G.Skill DDR3 1600MHz. All heatsinks on the board are stock and I have fans blowing over the MOSFET area for added stability. The video card is a 4850 1GB with VF830 running in the top slot. The board is sitting on my desk alongside my Odin 1200W PSU and DVDRW and HDD drives.


• The watercooling loop I'm using is very untraditional, but allows me to test the way I want to test.
  • It consists of a two MCR320s with three pairs of Yate Loon D12SH-12 fans in push/pull on each radiator. I use a D-Tek DB-1 pump on the radiator subloop.
  • For the block subloop, I use a Swiftech GTZ for its consistent mounting and a Laing D5 at setting 5. Also in the loop are three Laing DDC3.2s (turned off) as well as a Koolance KM-17 flowmeter to monitor and ensure there is no change in flowrate during a test or between tests.
• I use a shared Bitspower reservoir between the two subloops.


• I do a five mount test, each with their own TIM application and full cleaning between. I'm fond of semi-discarding the best and worst mount data--I present it to the reader, but my final analysis and numbers are all based on the median three mounts. As a reviewer, I feel it is my duty to present the reader with performance numbers of a product that represent what its typical performance is. Often times the best and worst mounts are somewhat anomalous; by performing five mounts and focusing on the middle three mounts (in terms of thermal performance), I feel I am best representing the expected performance of a product.


• I have 26 temperature probes in use: 22 Dallas DS18B20 Digital one-wire sensors and 4 Intel DTS sensors in the processor.


• For temperature logging, I use OCCT v3.1.0's internal CPU polling that is performed every second on all four DTS sensors and is automatically output to .CSV files. I also use OCCT for loading the CPU. For air intake and various water temperatures temperatures, I use Crystalfontz 633 WinTest b1.9 to log the Dallas temp probe data on my Crystalfontz 633. I also use WinTest b1.9 to log pump RPM and Koolance FM17 flowrate output. I have found, much to my chagrin, that programs like RealTemp, CoreTemp, Everest, etc., all have their own massive flaw in temperature logging that prevent them from being used for such a test. These flaws range from data formatting issues, to sensor polling issues, to random, yet common, stalls in the software (especially when logging).


• For processor loading, I find OCCT v3.1.0 to be extremely competent. With the Small Data Set setting, it provides a constant 100% load (so long as WinTest b1.9's packet debugger is fully disabled) and is extraordinarily consistent. It allows me to, in one button push, start both the loading and the logging simultaneously, which helps. I immediately also start to log the Crystalfontz data via WinTest b1.9. I run a 12 hour and 5 minute program, the first minute is idle, then I have 12 hours of load, and then 4 minutes of idle.


• I have found that simply using processor temperature minus ambient temperature is not adequate for Intel's 65nm Core 2 processors. However, I have found that ambient and core temps scale perfectly fine (1:1) with i7.

Installation Notes and Procedures

Indigo Xtreme

Being an entirely different form factor of TIM, it's not surprising that Indigo Xtreme has a new installation method. Included with every kit is a six page information and instruction guide, within which there are roughly four pages of instructions that you must follow carefully. Every step is there for a reason and it's crucial that you install it as prescribed. While four pages sounds bad, installation of Indigo Xtreme is actually pretty easy. The first time you do it, it feels a little foreign, but once you do it once, it feels like second nature after that and you'll be able to do it quickly. In the grand scheme of things, the only difficult thing about it is that it is different.

Here is a quick picture tour of the Indigo Xtreme kit and what's included.

The box the kit comes in:

First opening the box:

A view of the two kits included (only one includes gloves):

A view of a kit opened up:

Here is my summary of mounting Indigo Xtreme:

• If switching from another TIM and using watercooling, save your overclock settings (either on a piece of paper or to CMOS) and set your CPU to stock speeds and voltages. If on aircooling, set stock speeds and overvolt slightly.
• Shutdown, tear down, and orient the PC so that the motherboard is horizontal to the ground. Not sorta horizontal--actually horizontal.
• Clean the CPU and base of the cooler with the included supplies (wear the gloves!). The clean room cloth and solvent wipe are great! You'll probably be looking online to find where you can buy the solvent wipe because of how effective it is (though it is a bit smelly).
• Install the CPU and open the little case the Indigo Xtreme comes in...peel off the plastic layer labeled "bottom." Place it on the CPU as directed.
• With your finger and using moderate pressure, tap downward over the entire IHS of the CPU. This step is more important than it initially sounds.
• Peel off the plastic labeled "top" and remove your gloves and install your cooler with even pressure (like normal). You can leave the gloves on if you want, but thumbscrews are really tough to use while wearing them.
• Start up your computer and boot into windows. Open SpeedFan and start charting your core temperatures. Your temperatures will be really bad, that's normal.
• Start a constant loading program, OCCT, Prime, etc. (Linpack variants might not be that great for this due to the lack of a constant load). Unplug the pump or your fan (pump for watercooled setups, fan for aircooled setups). Yes, it's okay. As a test, I ran mine under load for approximately five minutes without a pump on; it sounds scary but it works fine.
• Watching SpeedFan, your core temperatures will max out almost instantly. Again, it's totally fine. If you're watercooling, your temperatures will drop from 99-100 to the 80s after roughly 10 seconds, let it run for a bit more and then you can plug your pump back in and then let it run for about a minute to cool down before shutting down. I left my pump unplugged for a minute each time, it worked great for me. For an aircooled setup, this process will take a little longer--roughly 5-10 minutes. Just be patient, it's worth it.
• You can turn your computer vertical again, or however you want to run it. You can start your computer at your overclocked settings and run to your heart's desire. You're all done installing Indigo Xtreme!

AS5, MX-2, ICD, and Shin-Etsu

Thermal Test Results

Specific TIM Tests

AS5 has a pretty large break-in...in the first hour (especially the first few minutes) it performs horribly and then slowly eases downward into better temperatures. In my opinion, at the end of twelve hours, it is still not fully cured, though it is close. The 'bump' at 60 minutes is due to the moving average calculation no longer including the really bad temperatures from the first few minutes of load.

MX-2, despite being noted as "non-curing," definitely has a break-in period. I estimate it at roughly 6 hours.

IC Diamond has a nearly linear break-in trend over the first twelve hours of load. It does not appear to be fully cured by the end of the test.

Note: only three installations of Indigo Xtreme were provided...due to the extremely close results between mounts, I feel very confident in the data. There was no break-in time.

X23-7783D has the shortest curing time of any of the pastes; it takes roughly 4 hours.

Thoughts and Conclusion

Without a doubt, Indigo Xtreme is the performance winner here. Considering how cool running my CPU is, even a ~1C improvement over second place is notable, but a ~2.5C improvement over the most popular TIMs is the highlight. With hotter CPUs (such as with a lot of Core i7 D0s), the gain is even larger. This is one of the last noticeable gains we may ever see in regards to TIM...we're rapidly approaching the limits of TIM peformance with the Indigo Xtreme. That is, the thermal resistance is so low (as measured by industry standard tests 1, 2) that any improved TIMs, even a theoretical TIM with a thermal resistance of 0.00, will net only a tiny gain. That's not to say that we won't welcome an improved TIM further down the road (any gain is a gain), but this brings us to the threshold of passive TIM performance. I've included a chart plotting the temperatures I obtained in testing against the documented thermal resistance of the TIMs. I'm not sure what the bondline thicknesses (BLT) were in my tests or the specifics of the ASTM D5470 test (especially regarding cure time), but the data it produced seems to correspond pretty linearly with both my 60 minute data and my concluding temperatures data. On my testbed, a theoretical TIM with zero thermal resistance performs only a fraction of a degree better than Indigo Xtreme does. The impressive thing is that Indigo Xtreme is a real product and it's available now.

I really like doing a review where the data can largely speak for itself, and this review is no exception. The performance of Indigo Xtreme is exemplary and easily makes up for any perceived negatives you've picked up mulling through this review. The second place TIM, Shin-Etsu X23-7783D, is the best performing paste-based TIM in this test and is a great option when you cannot use Indigo Xtreme. As for the others, they may not be the best performing TIMs in this test, but there's a reason they're some of the most popular TIMs in the enthusiast community--the performance they offer is good enough for a lot of people. But there are big gains to be had for those who want it...the performance of Indigo Xtreme is awesome and brings enthusiasts to the threshold of TIM performance--all in a form-factor that's surprisingly easy to use and cleans up easily.