AlkalineFoghttp://www.lazygamer.net/general-news/nvidias-gtx970-has-a-rather-serious-memory-allocation-bug/
Apparently it was the benchmark that was bugged, no problem with the 970.
Wrong.
http://hardware.slashdot.org/story/15/01/24/200256/nvidia-responds-to-gtx-970-memory-bug
NVIDIA states that "to optimally manage memory traffic in this configuration, we segment graphics memory into a 3.5GB section and a 0.5GB section" and that the GPU has "higher priority" to the larger pool.
This is a real issue and if you attempt to address the last 0.5GB of memory you will get terrible frames.