The Nvidia RTX 4090 takes the crown for the fastest graphics card currently available, but it’s not without concerns. Of course there’s the extreme price, theoretically starting at $1,599 but typically selling for over $2,000 right now. There’s also the matter of size. The smallest of the traditional RTX 4090 cards takes up at least three slots, often overlapping into a fourth slot. If you want to build a custom liquid cooling loop with a compact RTX 4090, though, Alphacool has a solution.

Optimum Tech posted a video review of perhaps the smallest 4090 water block currently available, the Alphacool ES Geforce RTX 4090 Reference Design with Backplate (opens in new tab). There’s a compatibility list for various GPUs (opens in new tab), but the cooler in question — model number 13395 — currently only shows compatibility with a few models. One of those models is the Inno3D used in the video, another is the KFA2 RTX 4090 SG, which should be the same as the Galax RTX 4090 SG (opens in new tab). Sadly, neither one of those is readily available in the US.

There are plenty of other RTX 4090 water blocks out there, including some single-slot options from EKWB, but none are as compact as this Alphacool model. Of course, you still need to add in the rest of the liquid cooling loop, and with a 450W TBP, going with dual radiators would certainly be warranted.

This particular cooler isn’t really designed for home users, though, even if it can work there. It’s part of the Enterprise lineup of coolers from Alphacool, with the idea being you could potentially stuff up to four RTX 4090 cards into a single server or workstation. At that point, you’d probably want to tune the cards to run at a substantially lower power limit like 300W, which would make this into something of a “poor man’s” version of the RTX 6000 Ada — with half the VRAM.

That’s an interesting value proposition, though, replacing a single $6,800 (or more) professional card with multiple consumer grade cards. There’s definitely more overlap happening between Nvidia’s professional line and the GeForce line, and the current prices on RTX 4090 cards still tend to hover in the $2,000 and higher range. That’s a ton of cash to plunk down on a gaming GPU, but if you’re doing AI training and inference — including Stable Diffusion — 3D rendering, or other professional work, it might represent  some sort of ‘bargain.’

Hopefully, someone will take the time to build a quad-4090 setup using something like this Alphacool waterblock, and then post a video and pictures. Because for a lot of us, that’s about as close as we’re likely to come to buying such a card.