Preface
This is my review between a few of the heavyweight paste-based TIMs and a newcomer to the TIM scene: Indigo Xtreme. You might have seen a few threads about it on various forums back in May--it was LGA775-only then, way more expensive than it is now, and untested. Well, they've expanded their offerings to LGA1366 as well, reduced the price significantly, and are working on getting it tested. I think my review is the first to go up with it and I've been incredibly impressed by it. Below is an abbreviated version of the (lengthy) full review at my backroom at skinneelabs....here's a link: http://vapor.skinneelabs.com/TIM/IndigoX/IndigoX.html

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.

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
A single 12hr test per mount with 5 mounts was completed for each TIM. Everything was held consistent between tests and everything was logged.

  • 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.

Each Indigo Xtreme kit includes two sets of installations, each including the following materials (only one set of gloves are included):


The clean room cloth and the solvent wipes are really awesome...the wipe is smelly, but it's one of those "wow, this will work well" kind of smells

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!

It's really not that bad, I thought it was going to be pretty daunting when I first looked at it, but it's a seamless process Yes, it's harder than squirting some paste on a CPU, but it's way easier than Coollaboratory's Liquid Pro and doesn't include any especially difficult hard steps.

For reference, here's a picture of Indigo Xtreme mounted on the CPU before removing the "Top" plastic piece.



Thermal Test Results
Yay, results!


Note: "Concluding Temp" is the average of all temperatures once the TIM stays below .1% above final temperature. In the case of Indigo Xtreme, MX-2, and Shin-Etsu X23-7783D, it is indicative of performance once broken-in/cured. AS5 and ICD are still curing at the end of twelve hours and I would expect their eventual temperatures to be lower after a full curing session.

Specific TIM Tests
AS5:


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:


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

IC Diamond:


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.

Indigo Xtreme:


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.

Shin-Etsu X23-7783D:


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.

(click on the image for a version that includes the data from all the timesets)

In terms of non-performance factors, the only downsides are the atypical installation and cost. At $20 for a kit (2 installations), it's more expensive than its competitors. But for most setups, the improvement it brings will be the most cost-effective upgrade possible for them. Blocks, radiators, pumps, and fans (when bought in multiples) are almost always more expensive and don't necessarily bring such a noticeable improvement in performance. I've already covered the installation--I think it's a non-issue; I've used Coollaboratory's Liquid Pro and Indigo Xtreme is a heck of a lot easier than that. It is harder than squeezing out some paste on a CPU, but that's not saying much. In terms of removal, it's the easiest TIM I've ever used. The entire unit (or 'card' as I called it previously) comes off in one piece. If any sticks to the CPU or the cooler, you can easily scrape it off with your fingernail or a credit card.

As for special notes regarding the other TIMs, there's not too much to say. For applications where an Indigo Xtreme is not viable (everything but LGA775 and LGA1366 at the time of writing), Shin-Etsu X23-7783D looks like a great paste-based TIM to use. It has the shortest cure time of the paste-based TIMs (even shorter than MX-2, which is noted for being non-curing) and the best performance. It's a pretty dry and thick TIM, so you have to use a medium amount of it (meaning you can only get 6-7 installations out of a 1g tube) and it's a little difficult to work with, but it's still a great performer and an easy second place in this test.

MX-2 still has a special place in my heart--and still a great tester TIM considering its ease of use and value in a 30g tube. For my own waterblock tests, where I use the same installation over the course of 8+ hours of testing, I'll have to let it break-in first. But for most testers, as long as they use it consistently (i.e., mount-and-go or allowing a consistent amount of cure time), there should be no issue. Hopefully it does not get phased out with the launch of MX-3 as it truly is a great paste.

The verdict on IC Diamond is still out as far as I am concerned. It's clearly not done curing over the course of my 12 hour test, and it's performance is pretty good even without a full curing session. It's also a really thick TIM, requiring a large amount to be used, meaning you don't get many installations from a 1.5g tube. It's also really good at polishing--as you can see from my pictures, the IHS of my CPU no longer has Intel's markings. I'm not a fan of that particular property of the TIM, but all things considered, IC Diamond isn't too bad. Between Indigo Xtreme, Shin-Etsu X23-7783D, and MX-2, I can't think of a situation where I'd have a use for IC Diamond, but it's definitely good paste overall.

Arctic Silver 5 is showing its age. It's competitive, but considering its numerous downsides (being capacitive is the biggest), I just don't feel it's a superior TIM to any of the others in this test. In terms of raw performance, it came in last. Arctic Silver recommends a 200hour break-in period with multiple power cycles, none of which I did, but I just don't see it jumping ahead and making up for its other deficiencies.
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.