It has been the middle of 2015, The version 7 of CentOS has been released for a long time and a major upgrade of Linux kernel -- 4.0 -- was released about two months ago, so I think it's time we keep up with the pace of software development. If CentOS does not want to upgrade the kernel because of steadiness consideration for example, let's do it ourselves!
I'm using CentOS 7 with 3.10.0 kernel. Following the article here, I successfully upgraded my CentOS 7 to the latest 4.0.5 kernel. It works very well on my machine. To simply put, the steps to upgrade the kernel to 4.0.5 on CentOS 7 is:
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
yum --enablerepo=elrepo-kernel install kernel-ml
(5) In the boot menu, select 4.0.5 kernel (usually in the 1st line).
After boot, use
uname -r to check the new kernel version.
PS: That article also contains ways to upgrade kernel to 4.0.5 on ubuntu.