An enclosure built from the ground up for custom liquid cooling loops is actually a fairly rarefied thing. Why wouldn't it be? Building a custom loop is expensive and time consuming, which would make that type of enclosure the very definition of niche. Yet Corsair has come forward with the Obsidian 900D for one big reason: to fill that niche.

And "big" is definitely the operative word. Riding high on their liquid cooling legacy with the popular Obsidian 800D, Corsair has developed a positively massive enclosure that's designed essentially to hold the most powerful desktop machine you can conceive of while providing ample space to mount radiators and all the accoutrements of liquid cooling.

Before we get too much further into this review, I want to be absolutely clear about how the Obsidian 900D is being evaluated, because it's a very different beast from most cases. It superficially looks and is built like an overgrown ATX case, but at an MSRP of $349 it's about as premium as it gets. When you see the way Corsair designed it, you'll be able to tell like I did that it's destined for much more than a garden variety build.

What that also means is that while I have to put it through our conventional testing, that conventional testing is going to be primarily academic. Unfortunately it's much harder to tell how good an enclosure will be at its job when that job will vary from person to person in much more significant ways than just choosing which air cooler and graphics cards to use. What you're going to want to pay attention to are the feature set, ease of assembly, and overall design, and how they're going to suit your purposes. That's assuming you're in the market for a specialized case like this, and a lot of you won't be.

Corsair Obsidian 900D Specifications
Motherboard Form Factor Mini-ITX, Micro-ATX, ATX, E-ATX, XL-ATX, HPTX
Drive Bays External 4x 5.25"
Internal 9x 3.5"/2.5" (support for two additional cages for up to 15x 3.5"/2.5")
Cooling Front 3x 120mm intake fans (1x additional internal 120mm fan mount behind drive cage)
Rear 1x 140mm exhaust fan
Top 4x 120mm fan mounts (supports 3x 140mm)
Side 8x 120mm internal fan mounts (four per side, PSU blocks two of your choice)
Bottom -
Expansion Slots 10
I/O Port 4x USB 2.0, 2x USB 3.0, 1x Headphone, 1x Mic
Power Supply Size ATX
Clearances HSF 170mm
PSU 280mm
GPU 500mm
Dimensions 25.6" x 9.9" x 27.2"
649.6mm x 252mm x 691.6mm
Weight 41 lbs. / 18.6 kg
Special Features USB 3.0 via internal header
Multiple removable drive cages
Secondary power supply bay
Removable filters on all fan intakes
Price $349

Corsair's press materials highlight the fact that the case is designed for liquid cooling, but you've probably figured that out given how much I've repeated it. What you're going to want to know now are the radiator clearances, and they're a doozy.

The top fan mounts have a 110mm clearance from the roof of the case to the top of the motherboard and you can intrude on the top 5.25" bay. Unfortunately in the front of the case, there's a slight spacing between the topmost 120mm fan and the two bottom ones, so that essentially means you can only install a single 240mm radiator; there does appear to be space to install a single 140mm radiator and fan instead if you're so inclined. The back of the case supports a single 140mm radiator in the exhaust fan slot. Corsair keeps the other bulk of radiator potential in the bottom of the enclosure, where you can theoretically install a 480mm radiator on one side and a 240mm radiator on the other, with 110mm of radiator clearance to the PSU. Note that installing a radiator in the bottom chamber does mean sacrificing those drive cages.

In and Around the Corsair Obsidian 900D
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  • dylan522p - Tuesday, April 16, 2013 - link

    The 900D has probably the most space on the side pannel for cable management I have seen in a case. The 900D also supports a stupid amount of rad support.
  • garadante - Tuesday, April 16, 2013 - link

    Remember, the 800D is three and a half years old. I don't think closed loop dual fan radiators were even available, let alone 4-way SLI/crossfire being as comparatively mainstream as it is nowadays.
  • santiagoanders - Tuesday, April 16, 2013 - link

    Why no comparison to the Cosmos II? Similar layouts and price.
  • praktik - Tuesday, April 16, 2013 - link

    Actually I think biggest competition for this would be the silverstone TJ11 - offers a 4x140 rad option in bottom if you take out the cages... also goes for 200 more....

    ...and yes I am a deliriously happy owner of a TJ11, my case for a decade - will go liquid cooling in a few years but right now just happy to have the air cooling equivalent of an FT02 to tide me over..
  • Sabresiberian - Wednesday, April 17, 2013 - link

    What do you mean "Why no comparison?"

    The article isn't lacking anything just because it didn't include data about your favorite case.
  • santiagoanders - Thursday, April 18, 2013 - link

    Because hardware articles always benchmark against the other products in the same market segment. WTF are you talking about?
  • scook9 - Tuesday, April 16, 2013 - link

    I like this case. Not enough to replace the 700D I got for $100 (including side window panel) but I like it. Having water cooled in the 700D I appreciate the changes. The 700D/800D really only has 2 good places for a radiator - a 360mm up top and a 120/140mm on the back. While this is a lot of cooling capacity (both can be double thick rads) the 900D obviously blows this out of the water and takes it to a whole other level.

    More exciting and likely to penetrate the market is the 350D that is coming out that is pretty much a mATX design using the same design ideas but being around $120. I hope that AT can do a review when that comes out and compare it to the all time favorite mATX case - the Antec Mini P180
  • noeldillabough - Tuesday, April 16, 2013 - link

    While this case rocks, it still doesn't hold a candle to my current favorite case, the TJ11. One of the problems with watercooling is that the board doesn't get any cooling and this case with its 2 giant (quiet) fans handles it with ease. Add to that a full size rad/pump/power supply fits in the bottom and I'm sold!

    Water cooling seems to be on its way out but cases like these make me think its only getting started!
  • OVerLoRDI - Tuesday, April 16, 2013 - link

    This case truly is for the water cooling enthusiasts. (I am one of them). If this had been around last summer I would have snatched it without a second thought.

    It makes me regret my Caselabs M8 purchase.
  • Biggestinsect - Wednesday, April 17, 2013 - link

    Never regret a CaseLabs purchase.

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