Sidenote: Six Months With A Custom Loop Watercooled PC – Some Thoughts And Observations

To kick off Blaugust 2021, I thought I’d write not directly about gaming…but about something gaming-adjacent.

Six months ago, I wrote about finally having completed my first-ever fully open-loop, custom-built watercooled PC. Instead of pre-made all-in-one coolers, as my last system had, this one is a single loop, with tubing I cut to length, fittings I selected, waterblocks I chose, and a radiator layout designed to maximize the case space, using six 120mm fans worth of radiator capacity to cool my CPU and graphics card, compared to my prior setup, which used an AIO cooler with a 3x120mm radiator just for the CPU and a hybrid graphics card cooler from EVGA that used a single 120mm radiator to cool the GPU and VRAM.

I wrote about the process of building the initial system and loop, which you can read here. Fun fact – that post was the point at which I upgraded to WordPress Premium, in order to share the leak test video!

So, after six months of use, a CPU upgrade, and a move, how do I feel about watercooling?

I’m Still Nervous With It, Albeit Less

Because custom loop watercooling means you are personally responsible for most leaks, unless you can prove a faulty O-ring or something of the sort, I was extremely paranoid about the system. That has given way over time, as the system has functioned exactly as I would expect it to, but there have still been moments where I’ve retightened fittings, excessively doted over it, or the like. When we moved last week, I refused to let the movers so much as touch my PC – I, instead, put it into the passenger seat of our car, wrapped it in a blanket to pad it, locked it into place with the seatbelt, and put my arm on it the whole time to brace it like a mother who does that instead of adjusting her braking.

However, so far, so good – it’s all been fine!

Temperatures Are Less Impressive For A Single Loop Than You’d Hope

At this point, I feel confident in saying it – a single loop for all your heat generating components isn’t going to be an earthshattering cooling experience. It’s fine, and better than an air cooler for the GPU, but across both my Ryzen 9 3900x and 5900x in this system, the CPU temps have been about the same as a good AIO liquid cooler or very beefy air cooler. Mind you, this is quieter than either of those, but if you expect to be able to push your CPU to the ragged edge for daily use, a dual loop with dedicated CPU cooling capacity might be better. By having the GPU in the loop, the water soaks up a lot of that heat and thus there just isn’t as much heat capacity in the liquid for the CPU to stretch.

Having said that, though – a big part of modern CPUs, especially the newest Ryzen parts, is using all available power and heat limits to push performance to the edge, and for my 3900x in this new system compared to the old, it ran faster and overall at higher boost clocks, and the 5900x has run splendidly.

Water Levels Can Fall Off Over Long Periods Of Time

I knew about the need to bleed a new watercooling loop, which is the process of running it for a long period of time to work air bubbles out of trapped corners in radiators and the like so that the system fills properly and fully with liquid. What I wasn’t fully prepared for (and was thus very nervous about when it happened!) is that the process of bleeding, which is usually described as a single act that takes a few hours, can sometimes take weeks or months for everything to pump through and for particularly stubborn air pockets to work their way out. When it finally does happen, it will look as though the system has lost water, because the reservoir will be visibly lower, but as it turns out, nope – just air working its way out! Now, there is a danger of microleaks too, where a fitting might be just loose enough that a few droplets leak and are evaporated before doing any lasting harm, or a radiator tube puncture – things like that where small amounts of water push out of the system, and those are problems to watch for (when I first saw my reservoir drop levels slightly, I definitely panicked and tightened every fitting up again!). But it is also normal, because…

How You Mount Your Radiators Matters (A Lot)

My system is built in a nice, budget Cooler Master case, which has a front panel setup allowing for 3x120mm fans, and thus, the biggest and easiest mounting point for a 360mm radiator. However, there’s a dilemma with that which I wasn’t ready for – no matter what orientation, you’re going to be fighting air pockets at the top. If you have the fittings at the top (as I do), then the inlet and outlet have small gaps above them where air will, quite often, be trapped. It can take a while for liquid to finally work its way up there, especially when said radiator is the last stop on your loop before returning to the pump, because the inlet will be the lowest flow and head pressure in the system, while the outlet will have a suction effect of sorts pulling liquid through into the pump. It took nearly 3 months and a handful of extra shakes and pivots of the case for me to finally get the air pockets out of the top of that radiator and to unlock the full cooling capacity of the system. Radiators earlier in the loop can also suffer from that type of effect, because the loop will create movement out of the pump and into the pump, which means that anything in-between may not always fill up. This also goes for waterblocks on your components, by the way – so be especially wary for those!

Water Temperature Is A Key Indicator Of Performance But Tells You Little About The Hardware In The Loop

The most critical measure of a watercooling loop is the liquid temperature. You want to ensure it does not exceed the rated temperature of the tubing you are using, as that can weaken the tubing walls, causing kinks, collapses, or even breaks. My loop fluctuates from between 24 Celsius and 39 Celsius, depending on the use, and the tubing is rated for 60 C, so all is well there.

However, despite seeming like a good measure to watch for loop performance, it often just isn’t. You do want to know what temps your loop is running at to avoid problems – climbing temps with no dropoff or especially climbs at idle can indicate a pump failure, but it also becomes a point for a chronic worrier to fret endlessly about. For me, something I noticed pretty quickly is that the liquid temperature is very easily swayed by room temperature – a few degrees warmer or cooler in your house and the liquid temps will spike or drop, so in the winter, my system typically ran cooler because we didn’t keep the heat that high and I closed the vents for heat in my office area. Likewise, in the summer, the loop runs warmer, because the average room temp is higher, and then it quickly drops off as air conditioning kicks on and brings the ambient temperatures down. In both cases, the system ran about the same, with actual component temperatures about the same.

Watching the loop temp is fun to see what things might be unexpectedly hard (running World of Warcraft keeps temperatures around 33 C in the loop, but for whatever reason, I can spike to 36 C if I idle in the Heart of the Forest in Ardenweald), or what games are easier to run. Something that impressed me was that Final Fantasy XV was often cooler-running on the loop than Final Fantasy XIV, and while both games look great, FFXV has a lot more eye candy!

So basically, you do want to monitor liquid temperatures as a safety measure, especially on a new loop, but stressing over it can be counter-productive unless a danger zone is approached.

I Value Silence More Than I Thought

My last system had a total of 13 120mm fans, two AIO water pumps, and a GPU fan for the hybrid cooler on that card. It ran very loud, and I often let it ride with all fans at 100%, because the variation in speed making pitchy sounds bothered me more than the steady-state volume.

So I thought that I simply didn’t care that much about noise, because it wasn’t really bothering me in the last system!

However, the new one has only 6 120mm fans, a single high-efficiency pump, and nothing else…and I love it so much more. My wife has my old system fully now, and I can hear it quite clearly when it is on, and it unexpectedly bothers me so much more than it used to when it was mine. Not much more to say on that point, but it was quite interesting, and makes me wonder just how much I was tuning it out or if I was just used to it, because this system makes so little noise and I am a big fan of that.

Overall Thoughts

My thoughts now somewhat mirror my thoughts at the start of the process. I’m very happy I opted for watercooling, very glad that it came together without incident, and still somewhat routinely frightened by it and far more observant of the system than I was prior to watercooling. I still dread the day I will have to flush and refill the loop, but given that I know everything works now and the beginner dread is largely gone, I think I might be a convert.

Having said that, I maintain that not only is watercooling your PC with a custom loop not for everyone, there are very few people who it is for. It’s fun, and an interesting stretch of PC skills, but the end result in terms of both temperature and noise can be matched with a fairly well-built air cooling setup. That setup is also likely cheaper, but comes with its own challenges (mounting a massive heatsink for the CPU, finding a well-cooled aircooled GPU, and getting a good case with fantastic airflow and then dialing in your fan curves to your preference) but none of those challenges are “if you don’t tighten a fitting you can kill a graphics card it took you 3 months to find in-stock” so you know, there’s a definite tradeoff there!

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