Video memory running out while screenshotting

So this is an issue I've never had before. I was playing Overwatch on my Windows PC when I took a screenshot. It froze for a moment, then gave me an error saying that the GPU has run out of memory. I restarted my PC, tried again and it did it again. I have no other running programs using the GPU.

My PC's specs are an i7-5775c, 16GB DDR3, Asus Z97-A, Nvidia GTX 1080 FE.

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Edit: Screenshot resolution set to 9X. Native res is 1440p. Dropping screenshot res seems to have worked. Each screenshot that was taken (that worked) was over 1GB in size.