Nano'ing the Vega Sapphire Pulse 56 - Heat Sink modding

SunMystic

Minimal Tinkerer
Original poster
Nov 28, 2018
3
1
Hi guys.

First a short summary of how I got myself into the mess I find myself in :) Feel free to skip down if all you want is to read about my dilemma. I thought this information might be useful for others who can get their hands on a pulse easier than a nano.

I'm doing a DIY case build of a dual-boot hackintosh somewhat to S4 size specs. One of the greatest hurdles I've met is that the Vega 56 Powercolor Nano – which would fit the size requirement of my case – costs about 800$ (EDIT: I live in Europe and has to import the Nano from Newegg). The Vega 56 Sapphire Pulse costs 500$, and has (almost) the same PCB (it takes 2x8 PCI-e for power rather than 1x8 + 1x6).



I thought the 300$ I saved on the card could get me a good ways to better cooling than stock Nano has anyways, so I ordered the Pulse. Then, I went ahead and looked at cooling solutions. My power situation is perhaps somewhat precarious (HDPlex 400 DC-ATX, waiting for the 400 AC-DC and currently on a 220W brick with a 65W CPU). With undervolting and overclocking some people have said that the Vega 56 cards can perform like a GTX 1080 and I also love me a silent computer, so the cooling headroom I have been looking into is 200W-250W, although the card is rated at 180W.

First I looked into water cooling, but it's very difficult to get a pump, reservoir and radiator+fan combo under the S4 size specs. There are two water cooling blocks to choose from specific to the Vega Nano PCB, one from Bykski and one from Alphacool. Since AIO systems puts the pump in the CPU block, these are not useful for a build like this, and the two options I have seriously considered are the Airplex Modularity System 140 mm integrated pump from Aquacomputer and the Ion from XSPC. Both of these solutions would necessitate a size increase of the case which I'm reluctant to accept.

In aftermarket air cooling, the most useful GPU coolers seem to be ARCTIC aftermarket air coolers. From among the ARCTIC coolers the Accelero Twin Turbo II seem best because there would be no space for the backplate of later iterations anyway, and very importantly, because the heat pipes traverses the breadth of the card, which would allow me to cut it to length by chipping off the heat fins at the ends without touching the heat pipes. The ARCTIC coolers runs into the same business as necessitates a specific GPU block for water cooling, namely that it does not cool the whole card. This seems important on the tiny Nano PCB, where VRM and load balancers heats up quite a bit. Also, they haven't been updated in years and there is no official support for AMD GPU's. Then again, with small radiator parts fixed to important parts of the card, the ARCTIC cooling solution may work. Does anyone have experience cooling hot cards using a GPU aftermarket cooler and small radiators?

MY CURRENT DILEMMA
So all this research comes full circle. There are no great solutions. The Pulse stock air cooler won't work because it is too long. 27-28 cm, and it can probably be 18-19 cm, which means almost a third of the radiator length would stick out. I can still return the card and get the Nano. Otherwise, there's the option of modding the stock cooler.





I see two options. Either I remove the fins over the left third of the card and bend the heatpipes over a 40mm diameter. I am afraid this might damage the wick inside if a powder-type wick is used, and capillary action over the bend might be compromised. Furthermore, as the bend radius is 20mm, I need to remove at least 20mm of useful fins this far into the part of the radiator (or do some very difficult counterbending of the fins to retain airflow. In this scenario, I would then likely bend the heatpipes 'under' the radiator (to the top side on the above images).

THE BONKERS IDEA
The other option is to cut the heat pipes when I cut the radiator.



I would then 'simply' reseal them using compression fittings.



Doing so would be a somewhat involved process – ensuring semi-perfect water content in the heat pipes, bringing the water to a boil, then resealing when the water vapour has displaced all air in the heatpipe. The ambitious plan is to calculate ideal water content, add more, seal it up, test it, remove a bit, test again, remove a bit – and so on, until performance begins to deteriorate, then add water back. This might require more compression fittings/olives than I care to use.

I would use some non-hardening grease on the olives (middle part on the picture above) of the compression fittings to prevent gas transport. When the heat pipe cools, the water inside condenses, creating a near-vacuum. This lowers the boiling temperature of the water to be in the working temperature range of the GPU.

Initially this didn't seem like a good idea, but these fittings are used for natural gas, water, oil, etc., and if they can work for industry, they should be useful for a small home DIY project. Even if the seal fails and needs a few retries, the layout of my case is such that the leak would fall directly out of the case and onto the table, making diagnosing pretty easy.

I am currently pretty confident this would work the best and be the easiest solution, but I haven't been able to find any examples of others cutting open their heat pipes, which makes me reluctant. The only concern I have been able to pinpoint is if the working fluid of the heat pipes isn't water and dries out on the wick when I open it, but I have a hard time imagining a working fluid not wanting to boil off with a little help. The only serious contender for working fluid seems to be acetone, which I could probably also use if I wanted to.

If it works it is a pretty easy DIY fix to make any radiator conform to any smaller size. I think I'm 20$ out for the fittings and will probably be about 20$ out for the grease, making this a 260$ savings with improved cooling, IF IT WORKS.

What do you think? Is this completely bonkers?

(I'm new here, I hope I'm doing things as I'm supposed to. If not, feel free to point out errors etc.)
 
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SunMystic

Minimal Tinkerer
Original poster
Nov 28, 2018
3
1
I believe you would have to fabricate a custom mounting bracket to use the Accelero with a Vega GPU...

Take a look at these which have the proper bracket for Vega GPUs...

This one says it fits with AMD, though none of the reviews mention VEGA. I believe you.

Even if it did though, I'l reiterate that I don't think it's a good solution to use anything but full-size heatsinks for a Nano PCB due to the temp profile of the card. My plan isn't to use an Accelero. I just wanted to discuss my issues with it, as it seems to be the only aftermarket air-cooler with heat pipes oriented in the 'breadth' direction, allowing cutting it to the 18 cm necessary for the card to fit.


Not if you live in the US. I have to import to Denmark, though – sorry I forgot to mention that. The Nano hasn't arrived in Europe yet. The Pulse has, and that helps a lot on the prices. I redid the conversions more accurately and it comes out to the Nano costing $740, and the pulse costing §470. So it's not $300 but $270 in difference. Still pretty big difference if you ask me.

Slight update: I think I'll buy a used card and try my luck with modding that first, and then if it works out, I can work on the Pulse. If anyone have experience with modding heat sinks I'd love to hear it. Alternatively, if there are solutions on the market...
 
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batterybull

Trash Compacter
Jul 28, 2018
43
11
Just put a downdraft cpu cooler on it, cutting and resealing heat pipes is a very bad idea. Heat pipes have to maintain a specific internal pressure to function, cutting it will destroy it unless you have some way of restoring that pressure when resealing.

I was just toying with the idea of attaching a C14S to a pulse 56 myself
 

SunMystic

Minimal Tinkerer
Original poster
Nov 28, 2018
3
1
Just put a downdraft cpu cooler on it, cutting and resealing heat pipes is a very bad idea. Heat pipes have to maintain a specific internal pressure to function, cutting it will destroy it unless you have some way of restoring that pressure when resealing.

I was just toying with the idea of attaching a C14S to a pulse 56 myself

Nice, I thought I couldn't be the only one wanting to tinker with it ;-)

I thought of using a CPU cooler too, but not too seriously, I'd have to admit. I haven't been able to find much about people doing it, and what's out there is old. I'd have to make a custom bracket solution or something, right?

There are solutions for controlling the pressure in the pipe as far as I understand. Essentially you want a near-vacuum in it. This is achieved by bringing the working fluid to a boil while the top end of the heat-pipe is open. When the working fluid has evaporated and displaced the air inside, you seal it. When the heat pipe cools and the working fluid re-condenses, you have your near-vacuum.
 

batterybull

Trash Compacter
Jul 28, 2018
43
11
I attached cpu coolers to gpus with 4 straight brackets each with 2 screw holes 10mm apart, if you can restore the vacuum then it should theoretically work, but seems like an excessive amount of work for an excessive amount of risk lol
 

thylacine

Minimal Tinkerer
New User
Jul 24, 2019
4
0
An old thread, I know, but Pulse Vega 56 is rated at 280W, not 180W according to Sapphire
More importantly though, how have you used your card in the end? I am thinking of putting it into one of those console-sized cases, would you maybe have some tips for the card?