OBJECTIVE
Water cool a high performance CPU and high performance GPU in the S401.
TLDR
I was able to fit the pump and XSPC 240mm Crossflow radiator in the S401 to water cool both CPU (R7 2700X) and GPU (RTX 2080 Ti) with acceptable thermals without heavy modifications (e.g., cutting out the backside of the chassis).
See the complete photo set
here (a few more photos than what Greasy posted above).
System Specs
Cooling Solutions
Alphacool DC-LT 2600 Ultra low noise ceramic - 12V DC
Alphacool DC-LT Plexi top
Alphacool DC-LT Individual Reservoir (13140) (temporary solution to bleed system)
EKWB EK-Velocity CPU Waterblock, RGB, AMD CPU, Nickel/Plexi
Alphacool Eisblock GPX-N Plexi Light Nvidia Geforce RTX 2080Ti M01 (11664)
XSPC TX240 Ultra Thin Radiator (120mm x 2) 20.5mm thickness + 22 FPI
ATP Surethane Polyurethane Plastic Tubing, Clear, 1/4" ID x 3/8" OD, 100 feet Length
8 KOOLANCE
Rotary Elbow Compression Fitting for 06mm x 10mm (1/4in x 3/8in), G 1/4 BSPP
1 KOOLANCE
Fitting Single, Swiveling Elbow, G 1/4 BSPP (used for the second right-angle down turn to Crossflow in-port)
1
XSPC G1/4" 10mm Male to Female Fitting V2, Chrome (spacer prior to the right-angle down turn to Crossflow in-port)
Distilled water +
PT NUKE PHN Concentrated Biocide
METHODS, RESULTS, AND LESSONS LEARNED
A single custom loop to water cool both the Ryzen 7 2700X and the RTX 2080 Ti (overclocked) is feasible in the S401 with a single 240 radiator to achieve acceptable temperatures during high-end gaming and to obviate any major modifications (such as cutting out the backside of the chassis to allow airflow from both sides of the GPU).
Just a 240 rad. That’s it. I was skeptical, too. I would’ve liked to put in a 280, but I've feared that to do so successfully may require cutting out the back of the chassis where the GPU sits (although I may be able to fit a 280 without modding – a hypothesis to be tested). At the moment I don't know of any 280 Crossflow radiators that could fit (needs to be less than 315mm in length, though a dual-pass 280 may work – there are a few 280 dual pass rads that are 312mm in length). But thus far, the XSPC 240 Crossflow has worked beautifully to control temps and allowed an efficient routing of the custom loop’s 1/4-inch flex tubing. While I was worried a 240 rad would not be enough at first, I found that judiciously selecting the appropriate fans can make a BIG difference. The fan solution I settled on works to cool the entire system with just a single 240 with this setup.
Fans Matter
For fans, I went through two sets of fans before I settled on the EK Furious Vardar 3000 RPM fans. They have some of the best CFM and static pressure I’ve seen. At first I didn’t think I’d be able to fit standard 25mm thick fans, but I was able to make the GPU + waterblock lay nearly flat on its backplate and it all fits (barely). Before I used the EK Furious, I tried EK’s Predator 2200 RPM fans (F4120ER) and got temps in the mid- to high-70s under load. I’m glad I moved to the Furious because they have superior CFM compared to the other EK fans:
CFM
EK Furious EVO (3300 RPM): 107 CFM = 181 m³/h
EK Predator F4120ER (2200 RPM): 77 CFM = 131 m³/h
Static Pressure
EK Furious EVO (3300 RPM): 5.81mm H2O = 57 Pa
EK Predator F4120ER (2200 RPM): 3.16mm H2O = 31 Pa
And even before I used the EK fans, I actually first started with two
15mm thin Silverstone slim 120s, which were very quiet at 2200 RPM max duty. However, the static pressure was suboptimal – meaning that although temps were controlled, it took
forever to cool down after load, even at 2200 RPM. The case was physically hot to touch.
Initial Custom Loop Setup (Failed)
And before all of this, I actually set up a
completely different custom loop that, ultimately, just didn’t work as well as I wanted with the small radiators. I got unsatisfactory temps with 2 small Alphacool radiators – the Alphacool Triple 50 (located at the front bottom of case just below PSU with only two 60mm fans mounted internally) and an Alphacool Triple 40 w/Noctua 40mm PWM fans floating in the space between PSU and motherboard. It just wasn’t enough radiator surface area to control thermals, which rose to 89C under load. Plus, the 60mm fans were miserably loud and untenable even though idle temps were in the 30s C. If I was going to go the tiny radiator route, I would’ve needed to squeeze in one more small one to achieve sufficient cooling to run fans at a slower speed and thus keep fan decibels acceptably low. I would’ve tried to add an Alphacool double 40 or a Magicool double 40 slim, but on the face of it I couldn’t see a way to do that comfortably with everything else in there without a drastic case modification.
Airflow Considerations
Ideally, you’d want the radiator and its fans unobstructed on both sides. Here, the GPU water block is directly underneath it. Although I was skeptical, I found the EK Furious Vardar 3000 RPM fans really do have the power to force air through the Crossflow and out the small spaces between the GPU water block and rad regardless of the GPU water block being a wall that somewhat obstructs the egress of hot air. The exit air flow pattern probably hits that wall and then looks for any crack out, so its path is probably very chaotic.
However, there seems to be more than enough positive pressure with these fans to force out the hot air and cool the system effectively. Yes, a 240 rad can cool a 2080 Ti AND a R7 2700X. Oh, and I overclocked the 2080 Ti to 1995 mHz; I kept the 2700X at its stock frequency of 3.7 mHz). To aid with internal cooling, I just added three additional 50mm Delta PWM fans (not pictured). One sits directly over the motherboard VRMs (under the return flow tube), and the other two to the left and right of the GPU waterblock inflow and outflow. I believe this helps under load.
Custom Loop Pump and Flow
Once again, the Alphacool DC-LT performs admirably for this SFF build. I’ve only done one other SFF build, an S4MINI, and I used this small pump exactly how I did here, too, floating above the North side of the CPU socket. It rests perfectly between the two Northern-most CPU compression screws and slides up under the lip of the top end of the case. If I used the CPU Velocity block in the MINI, however, the plexi block wouldn’t fit. In that MINI build I actually used a smaller profile CPU water block that I LOVE (the
Liquid.cool Strike ONE CPU Waterblock - AMD AM4, which is an even lower profile block compared to anything else I’ve seen and achieves the same results). To fit the block under the lid, I used a
low profile G1/4” plug by EK to seal the block.
Before closing the loop, I actually used a reservoir first to bleed the loop and then carefully removed it from the pump block via its 4 long screws. Alphacool builds this small DC-LT
reservoir that mates with the pump block/plexi top in a similar way to how some larger D5 pumps are configured with their reservoirs. The reservoir is very useful to add water and bleed the loop. There’s greater chance of spillage if only the plexi top is used. When the reservoir is unmated, the plexi top can operate on its own as a closed housing for the pump and the top plug allows easy access to the liquid to either adjust the water volume or add biocide as needed. There are some pockets of air in the loop, but it's fine.
CAVEATS and MINOR MODS
Aesthetics
I would’ve liked to sit the RTX 2080 Ti to the open side of the case, in other words, on top of the fans and radiator so we could see its clear plexi window and RGB (the water block is the Alphacool 2080Ti M01 [the M02 is sold out right now]), however the rad fans would be starved for air that way. To remedy that I’d need to cut out the back of the chassis in that spot. I may still do that if I upgrade to a slim 280mm radiator with 2 x 140mm fans. However, the drawback to that approach is the graphics card I/O is left with only one Display port that extrudes so much width-wise that it wouldn’t fit inside the case with the lid on if the radiators and fans were underneath it. Ultimately, I think I arrived at the best decision with these trade offs since I had to do very little modding to make the 240 Crossflow fit. Plus, using a Crossflow radiator instead of a dual-pass radiator allowed me to use more direct tubing connections. It’s just more straightforward and cooling is just as efficient (if not slightly more) than a dual pass rad. There's a good
Jayztwocents video on Crossflow vs Dual Pass radiators where he tests both and discusses the pros and cons. He also has a good video from a couple years ago that I believe still applies today -- it's titled
"Was a 240 Radiator enough?? Temp testing the ITX build." Jay concluded that a 240 radiator was "more than enough" for both CPU and GPU. And with this S401 build, I've arrived at the very same conclusion even though I'm using a slimmer rad than what he recommends (he recommended 30mm rads).
GPU I/O
Since the GPU + Water Block sits virtually flush on the back side of the case, most of the GPU's display ports/HDMI/Type-C are covered up since they don't line up with the pre-cut GPU slots. The entire bottom row is covered. Only the single top level display port is available. This could easily be fixed by cutting out that portion of the case. Maybe in the future.
Below are the small mods I made to make the graphics card lay nearly flat and ensure the 240mm radiator would fit.
Minor Modifications
- Removed metal block. I sanded down the middle rectangular block welded to the chassis just South of the motherboard – there's a row of them. This metal piece was interfering with laying the GPU nearly completely flat. The other blocks didn’t need to be touched (what are those blocks for anyway? Greasy informed me that they're for zip ties. Cool. Well one less zip tie-down).
- Removed the front USB 3.1/Type C connector. I also had to remove one the posts it sat on so the Crossflow radiator could sit as far down as possible in the bottom of the case.
- Modded GPU Bracket I/O area to allow the GPU bracket to reach farther back. If I didn't do this, the GPU wouldn't lay down as far as it could.
- Power Button Resoldering. I had to resolder one of the power button cables – I ripped it off messing around with different PSU configurations. As an aside, I found flipping the PSU vertically would have actually worked, and that flipping/reversing the PSU the other direction with the fan facing to the rear of the case would have also worked. I would’ve done just that to move the PSU right behind the power connector to free up space below the PSU to install the Triple 50 radiator. However, I’d have to cut out the back of the case to give the PSU air when it needed it (it doesn't spin all the time since it's Titanium-rated but I didn't want to take that chance of starving the PSU of air since it's fueling the power-hungry RTX 2080 Ti and would most certainly need to spin up under load). I avoided modding the case by going with the conventional PSU configuration.
- Shaved Power Cable. By shaving the top of the power cable, which makes contact with the top of the case, I was able to move the PSU closer to the top of the case. I gained about 5mm of extra space between the PSU and the GPU/Radiator/Fan complex by doing this. It made it easier to plug in the dual 8-pin PCI-E power cables. I shaved it with a Dremel barrel sander, which takes the plastic/rubber right off. I was concerned that I'd contact wires, but nope, there's TONS of plastic/rubber shielding on those things.
- Quarter-inch Flex Tubing. I routed the flex tubes in such a way that I can literally lift all the components out without disconnecting anything (radiator, GPU, and the Alphacool DC-LT pump). That gave me the flexibility to reconfigure and re-seat stuff AFTER I filled the loop with distilled water/PHN Nuke. Of course, I'm very cognizant that if this is done too much it puts stress on certain fittings and so I always keep an eye out for leaks. The only leak I've had was on the CPU-out fitting during initial filling. The fitting wasn't on tight enough (I apply fittings "tight-but-not-too-tight" at G1/4" base connections but I try to go "pretty tight" on the tube-side of compression fittings).
- PCI-E Riser. I had to use the 180-degree connector in lieu of the 90-degree riser block to make the GPU lay as flat as possible. It's 20cm in length, I believe. EDZY brand.
- Backplate Screw Replacement. I replaced the screws on the EVGA backplate (which I knew was a fantastic backplate per Jayztwocents, so I kept it, opting not to buy a third-party backplate) with low profile M3 screws. The original M3 screws on the backplate have a cylindrical head that is 2mm that pokes out way too far from the plate – they're not countersunk (that may have been a benefit of a third party backplate). Although I didn’t use countersunk screws to replace them, I used a very low profile hex top that’s <1mm and rounded. So I gained an extra 1mm of space simply by selecting different screws for the backplate. Every millimeter counts!
- Thinner Thermal Pads on GPU Water Block. I ended up having to discard the thicker Alphacool thermal pads because the water block wasn't making contact with the GPU. I had to get a flashlight to see in-between the card and the block to see if it was contacting the GPU and I could clearly see the gap. I actually gasped in that moment like Doc Brown from Back to the Future. I tore it down again and cut my own aftermarket thermal pads that were very thin (1mm I believe). They're the blue ones that are everywhere on Amazon.
CONCLUSION
It works. Huge thanks to
@grsychckn for creating a highly-portable SFF case that is capable of not only harnessing the power of a fully-powered desktop gaming computer, but one that can be completely water-cooled, as well.
