When talking about graphics cards, there is always the issue of reference or non-reference design. In this article, we will explain what this means and why it is important to know whether a card is reference design or not when considering a watercooling solution.
What is reference design?
Companies like NVIDIA or AMD develop graphics cards chips (GPU) and board layouts, the so-called PCB (Printed Circuit Board). The reference layout exactly defines the positions for the GPU, RAM, power supply regulators, power connectors and mounting holes on the PCB.
This is the reference design board of the NVIDIA GTX 980:
The distinction between reference and non-reference design is also made for the air coolers, which are presented by NVIDIA and AMD along with their new graphics cards models. With most reference coolers, the heat is dissipated through the PCI slot cover. Many coolers that are developed by the graphics card manufacturers themselves, have a tendency to dissipate the heat into the PC case. This places a higher demand on the cooling of the entire interior of the case, so that not too much heat is built up inside and other components become affected.
NVIDIA GTX 980 with reference cooler. Source: NVIDIA
When the graphics card manufacturers deviate from the reference layout for the PCB and cooler, they create so-called non-reference or custom design cards. There are also models, where they only modified the cooler and the PCB remains in the defined reference layout. For example, custom cards feature a higher clock and / or more memory. Non-reference air coolers often run quieter than their original counterparts and are more efficient, because they are equipped with more than one fan. Sometimes it also happens that the manufacturers are not allow to release any custom designs. Currently, this applies to the Titan series from NVIDIA.
Of course you can ask the question why one should decide to go for a watercooling solution. In general, a water-cooled PC is more quiet, radiates less hot and dry air and goes easier on the hardware itself. There should be no throttling with either the CPU or the graphics card. If you want to overclock your system, you have a wider range at your disposal, because the cooling capacity of water is better than that of air. In physics, which is expressed by the „heat transfer coefficient“.
Ocaholic did a direct comparison test in which they benchmarked the same card with the original air cooler and with a waterblock (ASUS DirectCU II R9 290X):
Even under full load and overclocked the watercooled card didn’t get hotter than 53°C, whereas the aircooled version ran at 81°C…
Putting the results into perspective shows, that the R9 290X with an aircooler is running really hot. It’s basically hitting the temperature limit as soon as there is heavy load and even the powerful DirectCU II cooler from ASUS is not powerful enough to eliminate throttling completely. On the other hand, if you put a watercooler on top of this card, then you can basically unleash the full potential of this card. This becomes especially clear as soon as you start overclocking the card. In our case it was possible to run the card stable even at 1310 MHz GPU clock, whereas the maximum with the aircooler was at 1150 MHz (Source: ocaholic.ch)
Reference design and watercooling
If you want to employ a watercooling solution with your graphics card, there are basically two types of waterblock to choose from: The first one only cools the GPU. The second one is a full-cover waterblock which not only covers the GPU, but also the RAM chips and power supply regulators on the PCB and thus ensures best cooling of the entire card. For high-performance graphics cards full cover coolers are recommended in any case.
The issue of reference design is not relevant in this case, because the cooler only uses the four mounting points located around the GPU – similar to the CPU socket on the motherboard.
Here are two examples from different manufacturers:
Watercool HEATKILLER GPU-X Core LT. Source: Watercool
Koolance GPU-220 Cold Plate. Source: Koolance
The GPU cooler from Watercool can be supplemented with a universal copper plate that fits on many graphics card models or can be tailored to fit. On the copper plate, there is a small block of POM (acetal), which is also connected to the cooling loop:
Watercool HEATKILLER GPU-X Core 60 DIY. Source: Watercool
This kind of cooler is cheaper to purchase than a full cover water block and you can continue to use it when you acquire a new graphics card. The disadvantage is however, that the rest of the card is not cooled actively. In the early days of water cooling for PC’s, it was quite common to use this kind of cooler.
Alphacool offers a system that is a mixture of full cover and GPU-only coolers. The GPU is cooled with a standardized waterblock, the rest of the PCB is covered with a passive cooler. This is in turn again adapted to the layout of the PCB.
Alphacool NexXxoS GPX. Source: Alphacool
Full-cover waterblocks are always built to fit a specific graphics card model or layout, because they must match exactly on all the positions of the components on the PCB. Therefore, a distinction is made between waterblocks, which are intended for reference cards and blocks that fit on certain custom designs.
On this waterblock from Watercool (Water HEATKILLER GPU-X „Black Edition“), you can see all the different recesses on the back:
When mounted on a graphics card (EVGA GeForce GTX 780 Ti SC), it looks like this (here we use the „Acryl Edition“ of the same waterblock):
When you are looking for a waterblock for a particular graphics card, you need to know if you have a reference card or not. If a card only has a custom air cooler, it still counts as a reference card when looking for a suitable waterblock.
- Reference PCB + reference cooler = reference card
- Reference PCB + custom cooler = reference card
- Custom PCB + custom cooler = NO reference card
Not all waterblock manufacturers produce for the market of reference and custom cards alike: EK Water Blocks regularly offers waterblocks for custom design cards, Liquid Extasy also specializes in the production of custom-made blocks. Manufacturers such as Watercool or Aquacomputer (see list below) are well known for their reference design coolers. Developing and producing different variants of a product is always an economic consideration for each manufacturer, because the product cycle of graphics cards is relatively short.
Next, we will use a concrete example to show you what all this really means and how big the differences between a reference and non-reference card can be. To do this, we have prepared two GTX 780 Ti models in two different versions:
Card on the left: ASUS GTX 780 Ti DirectCU II-OC (complete custom design)
Card on the right: EVGA GeForce GTX 780 Ti SC (reference PCB / custom cooler)
Waterblock: Water HEATKILLER GPU-X „Acryl Edition“
Comparing the two cards, the first thing you realize is the difference in size of the two coolers. Together with the cooler, the ASUS card is almost two centimetres longer than the EVGA card. In addition, it is more than three centimetres higher. Also, the two PCB do not have the same dimensions. The positioning of the elements on the PCB is not the same either: For example, the power supply regulators and the capacitors are arranged differently. The connection for the SLI connector rises above the rest of the PCB on the ASUS card.
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On the lower right, the waterblock and the EVGA card are superimposed. On the left, you can see the backside of block again for comparison. You can see clearly how the recesses on the backside of the block fit exactly onto the elements on the PCB.
The RAM chips are marked purple, the power supply regulators are shown in red and blue. For the two capacitors marked in bright red, you can identify the recess on the waterblock very well. In the middle, there is the GPU.
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Dimensions ASUS GTX 780 Ti DirectCU II OC (Link for technical details):
Length: 28. 7 cm
Height: 14.7 cm
EVGA GeForce GTX 780 Ti Dimensions (Link for technical details):
Length: 26.6 cm
Height: 11.1 cm
Selection of a suitable waterblock
To a certain extent, the search for a suitable waterblock is quite similar the famous “chicken or the egg”-question.
- I have a graphics card and want to retrofit: Waterblock manufacturers offer compatibility lists and configurators on their websites. By using them, you can find out if the manufacturer offers one or more suitable waterblocks or not. Basically, it also helps you determine, whether you have a reference card or not.
- I don’t have a graphics card: In this case, you can look at various waterblock manufacturers and select a block you like or one that has good reviews. The manufacturer specifies for which card the block fits. Of course, the card must be available to buy some place, otherwise you will have to continue looking.
Selecting a waterblock is also a feast for the eyes, as you can see here very nicely with this example:
Of course, you should also think about the other water cooling components and the layout of the loop inside the case, because ultimately a complete water cooling system consists of more than just the graphics card.
When new graphics card models are released, there is usually a certain time difference before waterblock manufacturers can deliver the right blocks. But of course they work very hard to keep the gap as brief as possible.
This list of GPU waterblock manufacturers can be helpful:
Before the installation
When you have purchased a suitable waterblock, we recommend the following procedure: The graphics card should be tested as you bought it. Let it run in your PC for a week or two, so that you can check it carefully and exclude possible defects. If a graphics card exhibits any problems, it becomes a case for RMA. The waterblock must be tested as well: make sure there is no leakage, clean it from the inside and seal the openings with caps.
Only after all that you should mount the waterblock: read the manufacturer’s installation instructions carefully and take enough time for all the necessary steps. With this approach, you can practically exclude that you retrofit a defective card or use a damaged waterblock.
If you decide to retrofit a waterblock on a graphics card, you should be aware that this may lead to the loss of the warranty. Not every card manufacturer handles this the same way. The same would also be true, if you install a different air cooler. For the warranty issue, the removal of the original cooler is the relevant step. Therefore, it is important to retain the original cooler under any circumstances. EVGA is known to provide the warranty even if the original cooler was dismantled, as can you can read on the FAQ support page.
One way to avoid such warranty issues, is to choose graphics cards models like those from EVGA or ASUS that already have an integrated waterblock. There are also shops that offer the retrofitting of a graphics card as a service to their customers (e.g. MIPS Computer).
Where you can get help
If all this sounds too complicated for you, consult forums for assistance for many watercooling topics or make use of the opportunity to ask questions in the community.
In German: PC Games Hardware / OverclockingStation
In English: overclock.net / bit-tech.net
We thank ASUS, EVGA and Watercool for providing the samples used for this post.