Core i7 Roundup #2
Swiftech GTZ and GTZ SE Installment
October 4, 2009



Intro

The Swiftech GTZ SE is the current flagship Swiftech block. It uses the same base and overall construction as the acclaimed GTZ, but uses a fancy chrome-plated brass top. It was debuted as a special edition with e-tailer Performance PCs, but has since propagated the entire scene and should be available everywhere. In fact, FrozenCPU recently had a sale for $40 GTZs, the SE included. I picked one up mostly to have a backup base and mounting hardware (mine have seen a lot of mileage), not expecting performance with the metal top to be different. I was wrong--the two blocks perform distinctly, even when using the exact same base. We'll explore why later.

The Swiftech GTZ is the recent flagship of Swiftech, only recently replaced by the GTZ SE. It brings a base design featuring 225µm (0.009") micro structures over the center of the block as well as a direct impingement design to direct and accelerate flow over the tiny pins. The external appearance is kept simple with just a black acetyl top with some branding features and an interchangable metallic mounting plate. The other big feature of the GTZ is the mounting system--it is designed to be the easiest and most consistent mounting system Swiftech has shipped to-date. It features large thumbscrews and a backplate that provide the right amount of mounting pressure every mount.

This test will focus on the performance of the blocks in general and over a large flowrate spectrum. Results from the installments of Roundup #2 will be compiled, as they're posted, into an Overall Comparison page.




Thermal Testing Methodology/Specification


Methodology

My waterblock testing methodology has evolved over the past few months and I think it's finally at a resting point where I can start piling up test results rather than tweak the methodology (and thus preventing cross-comparisons). I use Dallas One Wire DS18B20 temperature probes at various points through my watercooling loop and at the air intake to measure temperatures, I've isolated the radiators so that the flowrate through them never changes, I use six different pump settings for each block, and use good testing practice by performing 5 mounts. Where applicable, I will also test various modifications to the blocks. These include testing various orientations and removing/adding various midplates, nozzles, dividers, etc. In some cases I will also modify the mounting system and present results from increased mounting pressure. For my waterblock tests, I'll perform 5 mounts of each configuration for every waterblock. The best configuration will then go on to be tested through the full flowrate spectrum.

Specification


  • The processor I'm using for this test is my C0/C1 i7 920. I'm running it at 21x200 (4200MHz) at 1.52V loaded on a Gigabyte EX58-UD5. It is unlapped. I'm running 3GB of G.Skill DDR3 2000MHz. 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 Laing D5 and three Laing DDC3.2s for the pumps as well as Dwyer RMC-142 and RMC-144 flowmeters to monitor and track flowrates.
    • I use a shared Primochill 8-port reservoir between the two subloops.

  • I do a five mount test for each block configuration, 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 28 temperature probes in use: 24 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.

  • 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 1 hour and 40 minute program, the first minute is idle, then I have 95 minutes of load, and then 4 minutes of idle. The first 20 minutes of load data is considered warm-up and the last 75 are used for results.

  • 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.


Thermal Test Results


Now finally some results! First up, the individual configurations testing.



The first odd result I've ever had with my testing. For the record, the exact same base, mounting plate, bowing plate, o-ring, distribution insert, and mounting screws were used. The only thing changed was the top. The tops are, aside from material, identical as far as I can tell. Furthermore, the airflow over the socket I provide for MOSFET cooling is, at best, water temperature (it's usually .3C higher than water temps). So the "radiator effect" of a metal top is totally non-existent here. That really leaves one option--it's a structural advantage. The GTZ uses a very deliberate bow in its design and it seems the stronger metal top is more effective at implementing the bow. In turn, the GTZ SE does noticeably outperform the GTZ.

I do have a spare base here that's seen a lot of mileage (and isn't looking so good), but I'll use it to see if I can unlock some more performance, akin to what I did with the Heatkillers (the mods I have in mind require physical modification to the base). I'll report back if it's a fruitful venture.

Specific Pumping Power

Now that we've figured out what the best configuration is for each block, let's chart its performance over the entire flowrate spectrum.
  • Very High Pumping Power: All three MCP355 pumps and the D5 are on at full speed--this has a very similar PQ curve to a pair of RD-30s at 20V.
  • High Pumping Power: Two MCP355s with EK V2 tops are on at full speed. The other two pumps are off.
  • Medium High Pumping Power: A single MCP355 with XSPC V3 top is on at full speed. The other three pumps are off.
  • Medium Pumping Power: The stock D5 is on at full speed and setting 5. The other three pumps are off.
  • Low Pumping Power: A single MCP355 with XSPC V3 top is on at minimum speed (~7.7V, ~2450RPM). The other three pumps are off.
  • Very Low Pumping Power: The stock D5 is on at minimum speed--setting 1. The other three pumps are off.

Note: I do 5 mounts at "Medium High" then take the best config of a block and test the whole flow spectrum (after a TIM curing session) then realign that curve with average of the 3 median mounts to give you the "Adjusted" data.

Other Graphs

More graphs for your enjoyment...let's start with reusing the flow vs. temperature data, but including pump heatdump (i.e., CPU vs. air temps). I have two iterations of it: CPU temperatures vs. my air temperatures and a setup with my water-to-air delta included twice more. The latter is to mimic a setup with one third the radiator power of my setup (roughly a 120x3 radiator with 1600RPM fans).


Note: these results are derived from adding the water-to-air delta three times to my water temps. I add them three times to emulate the radiator power of a loop with 1/3rd the radiator power mine has. I use 2xMCR320s with push-pull 2200RPM Yate Loons and the data emulates the conditions of a loop with a single 120x3 radiator with ~1600RPM fans.

Here we can see both blocks showing benefit with all pumping power on my testbed. Like most blocks before it though, it's best performance with 1/3rd the radiator power is with dual DDCs. The GTZs like pumping power for sure.



Conclusion

This conclusion is as data-centric as any of my preceding reviews...I've been bundling blocks by maker and this is no exception. I was really, really surprised to see the GTZ SE perform differently than the GTZ, let alone by so much. The GTZ SE's metal top is clearly superior for the bow Swiftech induces. I would absolutely not extrapolate out these results to other metal top blocks, however. Each manufacturer implements their own form of bow (even if it hard to see, each one is unique) and there may be cases that the metal top options for other makers doesn't affect the bow at all. It's obviously something that needs further investigation.

As for the mounting system of the Apogee GTZ, it should be mimicked by all manufacturers. It's simply superior. It easily produces repeatable mounts with ideal pressure. I tried increasing the mounting pressure using washers between the mounting plate and the mounting screws, and all it did was make temperatures worse. Swiftech got it right, others need to follow.

The Apogee GTZs are great blocks...build quality is second to none and performance is very good. The mounting system is, basically, perfect.

 

 
 


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