Introduction

The Storm G5 is the latest waterblock design from Little River Waterblocks.  As we saw recently, the Storm G4 waterblock set new levels of performance for CPU cooling.   It has been no secret that Cathar would also release a higher performance (but higher cost) silver block (called the G5) to round out the Storm product line.  He was gracious enough to send one of the first batch of silver G5s to Procooling for testing. This is the final preproduction run, and if changes are made in the shipping blocks then this review will be updated.

The G5 uses the same basic cooling methodology as the G4, but jet density has increased and a pure silver baseplate was used instead of copper.  The middle and top plates are black Delrin (which will not crack), the barbs used on the Storm have a slightly larger inside diameter than normal 1/2" barbs (and are chrome).  As with the G4, the cups in the baseplate contain a small pin in their center to increase turbulence.  Here's what Cathar had to say about the Silver Storm G5:

"The G5 is a geometrical extension of the parent Storm design. It offers an increased density of the internal structure over the G4. The decision to use silver was made to give the block a bit of extra performance as I felt this was justified by the increased machining time where even the cost of the silver plays a secondary role in the overall cost of getting the block manufactured. I also decided to go for some additional bling factor too, with the universal mounting bracket being polished to a mirror finish. Where the G4 was mostly black with some contrasting silver, the G5 I wanted to be mostly silver with some contrasting black. In the end I was very happy with the final result's appearance and I was also somewhat surprised by its performance during internal testing.

I consider the G5 in silver to be my finest work to date."

 -Stew Forster aka Cathar of Little River Waterblocks

As with the Storm G4, there is a lot of attention to detail in the Storm G5 waterblock construction. The notched baseplate certainly improves the look of the block (and may even save a bit of money on material cost assuming the excess is melted down later).  The block fits together exceptionally well and simply "looks cool" in silver and white.  I don't spend much time looking into the side of my case at parts, but I think the combination of shiny silver and black will be a popular one for those of you who do. Just as with the Cascade SS, there's simply something about silver blocks that looks sweet.

The baseplate had been hand lapped and seemed to be reasonably flat and smooth.  Cathar warned me later that the process used on this block might have left a slightly warped base, but that it had been dealt with and later blocks will not have these problems.  Here's a picture of the Silver G5 with P4/A64 mounting plate installed:

Test Results and Observations

I finally got around to putting together a summary of my testing methods and equipment, so if you want to get the full lowdown on the Procooling test bench then just give that a read.  All testing was done with a TBred B 1700+ at 175x12.5 and 1.825V in BIOS (estimated to be 71W given the dT across wb).  Here is a bit more information on the "delta T" numbers that are used in all the graphs that follow:

 I measure CPU diode temperature, the temperature of the water at the waterblock's inlet, and the water flow rate.  By plotting the difference between CPU temperature and water temperature, we can normalize all testing.  This is required because water temperatures may vary from day to day in my testing room.  The closer that this delta T (engineering-speak for temperature differential) is to 0, the better the waterblock is performing.

The first test I conduct is the variation of waterblock performance over many mounting replicates at 1.50GPM flow rate. 

Over five mountings the average temperature difference between CPU diode and water inlet was 7.95C, and the standard deviation was 0.17. There were no problems when mounting this block or in reproducibility of the results. I actually replumbed and retested another block to make sure the system hadn't somehow gotten out of calibration; these numbers seem almost TOO good!    

The next test conducted is the relationship between waterblock performance and flow rate:

For comparison the Little River Cascade, Cascade SS, and Storm G4 waterblocks are also shown.  It is clear from this graph that the Storm G5 is the best block ever manufactured by Little River Waterblocks over all flow rates. It is interesting to note that at very low flow rates (0.25 ), the G5 shows performance equal or better to the Cascade and Cascade SS while the G4 performs worse than the earlier blocks. Since the influence of silver in the Cascade SS had a very small effect on performance at lower flow rates, I would suspect that the higher nozzle/cup density of the G5 is responsible for its improved performance.  This makes sense as more jets of smaller ID would lead to increased water velocity, and more cups of smaller size would improve surface area for cooling. As flow rates are increased to more realistic (0.5-1.5 GPM), the G5 just walks away from the other blocks.  The combination of increased jet/cup density and silver base result in an improvement of 0.5-0.6C over the G4 at higher flow rates. Rather by luck or by careful design, it is clear that the jet impingement is extremely optimized in the G5.

Of interest to most readers is the performance of the Storm G5 waterblock plotted versus other commercial blocks I have tested:

The Cascade SS was omitted from this graph because it was made in very small quantities and is no longer available. It may not be totally fair to include the Storm G5 in future graphs either.  I will look at availability and decide. This figure is getting pretty busy (though not so much in the Storm G4 and G5region), and I recommend either clicking on the graph or following this link to use Procooling's interactive waterblock comparison page.  The Storm G5 is the performance leader over all other commercial blocks at all flow rates shown.  The only really close competition from a pure performance standpoint is the Little River Storm G4.

This graph really only tells half of the story though because flow rates in a real cooling loop will be determined by the resistance of all the components.  As an estimate of expected flow rates in a typical system, Cathar has provided this graph (click to enlarge):

The final consideration when purchasing a waterblock is the price. The silver materials and the extensive machining time necessary to make something like the baseplate do not come cheap. The estimated price for this block is $250 AUD, or $192 US at the time of this review. Is the improved performance worth the cost?  That is in the eye of the beholder I suppose. I'm sure there are plenty of obsessed water coolers that will not be able to resist. Thanks again to Cathar for providing me the Storm G5 for testing.

If you have any comments or Questions please contact pHaestus@ProCooling.com