Colour Banding (Now Resolved)
Testing the screen with various gradients showed an issue which some early buyers have also reported to us. The above photo captures the problem. Red and green gradients are smooth as you would hope to see, with only some minor gradation evident, and being typical for most monitors. The blue gradient is an issue though and shows some obvious colour banding. You can see defined blocks / steps in what should be a smooth transition gradient from dark to light. This in turn affects the grey gradient shown at the bottom since that is an amalgamation of RGB.
We tested all the different OSD options to see if we could eliminate the problem but without any luck. We also checked all the graphics card control panel settings, ensuring full RGB range was selected and anything else we could think of which might cause the problem. The result was the same from our NVIDIA and AMD test systems and so is confirmed as a hardware issue.
This does appear to be an issue on the X34 as it can affect some images depending on the content. Solid colour areas or gradient type content will show this issue most, although in dynamic gaming etc it's much harder to notice. In fact day to day it was not easy to spot unless you went looking for it.
We have reported this issue to Acer to investigate and will update this review later on when we receive more information. Speculation that this might be a measure to allow for 100Hz refresh rate seems unfounded, since 3440 x 1440 at 100Hz is within DisplayPort 1.2 bandwidth specs without needing to adjust the colour depth. We suspect a firmware update could address this issue with a bit of luck. We would consider this an issue at the moment, and something likely to upset customers given the high price of an item like this. On the plus side, the screen is barely available anywhere yet. Stock is expected in the UK in a week or so although some retailers in Germany have already started shipping. We hope to see a firmware update from Acer to address this issue hopefully before it becomes widely available to buy, as it must surely be fixable given there were no issues on the XR341CK model using the same panel.
Update 23rd September 2015 (Banding Issue Now Fixed)
We have had confirmation from Acer UK that ALL UK stock arriving in to official reseller channels will have an updated V2 firmware installed by default which fixes this banding issue. This includes stock being sent to Overclockers.co.uk, Scan, Amazon and eBuyer. So UK buyers need not worry about this issue thankfully. We have tested the new firmware and confirmed it resolves the blue banding issue properly.
We have asked Acer to confirm the status of initial retail stock being sold in Germany, which at the time of writing seems to be the only early stock available and does carry the V1 faulty firmware. We will update this review again when we know what's happening with the small number of those existing units, whether the user will be able to update the screen themselves or need to send it back to Acer to do.
Again we have asked Acer to confirm the situation outside of Europe as well, particularly in the USA with stock when it arrives there.
Update 6th October 2015
Acer have confirmed that for any user who purchased the screen from the very early stock available in Germany, they would need to contact Acer service and support who will arrange a firmware update with them. We have been unable to confirm if Acer US stock will be fixed before shipment as we have been asked to contact Acer US directly for that verification. We would be surprised if it was not fixed when retail stock becomes available in the US though given it is a known issue and has been addressed elsewhere before release.