IME, with about 3mm between my SLI setup, an Accelero will not workout for you. They will be starved for air and with a GPU as hot as the r9 290 you are sure to run into throttling issues and the like. Most SLI/Crossfire owners suggest blower coolers, but this will obviously not suffice either as they are super loud, particularly AMD's reference design, which is more or less the only blower available.
I started with a blower, then tried the Accelero, and then eventually modded my cards with Kuhler 620s to get close to quiet. Unfortunately, with high-end GPUs in a multi-GPU setup there really is no choice but water if noise is a concern. So, I'd like to offer some clarification:
Water cooling adds pump noise,
While this is true, a modern pump with a custom top can be very, very quiet, inline with <700rpm fans. There are multiple threads here in the watercooling forum and many tests at Martin's Liquid Lab - pumps are not as loud as they used to be and can be dialed down and dampened to the point where a quiet fan at low speeds will be louder.
and turbulence noise from cooling the radiator.
This is true, but not a concern in a decent case, and also not very different from fans pushing air through a heatsink. With the decrease in temperatures you get from watercooling you need significantly less air to keep things cool. If your case has provisions for 3x120mm radiator (whether it's 1x360 or 1x 240 and 1x 120), you can get away with very low FPI radiators and low RPM fans to ameliorate any "extra" turbulence you might observe when compared to an air setup.
The only way it makes sense IMO is if you have radiator with a big enough surface area that you can cool it passively outside the case. Otherwise you're just shifting heat around inside the case.
This is the biggest justification for blower coolers in a multi-GPU setup. Most aftermarket cards and coolers push air out from the card and into the case, and with a second card cm's away, onto the second card, significantly increasing system and especially GPU temperatures. Blower coolers relieve this by exhausting the air outside of the case, but with the premium of a lot of noise from a) the radial fan and b) the radial fan having to push air through a very high FPI heatsink, and sometimes a vapor chamber.
While this is still an issue with watercooling, your 2x r9 290s won't be running at 94* on load, they'll be closer to 45*, making for much less heat, and rather than hot air being pushed around awkwardly over your PCI slots, you can arrange your radiators to ensure proper airflow for your case as most users mount their radiators on a case's intake or exhaust.
They also don't cool the VRMs as good as an air cooler.
I am not sure where you heard this but this is only true if you are using a universal GPU waterblock. Most users with high-end cards opt for full cover blocks, which will cool VRMs significantly better than any air cooler could hope to. This can be verified in any r9 290/x owner's thread on any enthusiast forum - users on air, even with nice aftermarket coolers, have VRMs pushing 90* on load while their GPU is less than 80* (this is true of Tri-X and Accelero). Users with a full cover block have core temperatures in the 40's and VRMs in the 60's.
Anyway, I'm not trying to convince you that your only option is water, and I have my own hesitations around watercooling (cost, setup, maintenance, cost), but, generally speaking, with multi-GPU setups it is the quietest and best performing option.