I have updated the BIOS. Thank you for the help.

sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

# SMBIOS implementations newer than version 2.8 are not
# fully supported by this version of dmidecode.
1101
# SMBIOS implementations newer than version 2.8 are not
# fully supported by this version of dmidecode.
10/01/2015

I can still see the warning in the logs:

Oct 16 13:26:53 fozzy kernel: [ 6733.169262] ------------[ cut here ]------------
Oct 16 13:26:53 fozzy kernel: [ 6733.169300] WARNING: CPU: 0 PID: 0 at /build/linux-qOmAV7/linux-3.19.0/ubuntu/i915/intel_display.c:
11100 intel_check_page_flip+0x11c/0x130 [i915_bpo]()
Oct 16 13:26:53 fozzy kernel: [ 6733.169301] Kicking stuck page flip: queued at 382627, now 382631
Oct 16 13:26:53 fozzy kernel: [ 6733.169302] Modules linked in: cfg80211 binfmt_misc dm_crypt nls_iso8859_1 uvcvideo videobuf2_vmall
oc videobuf2_memops videobuf2_core v4l2_common videodev snd_usb_audio media hid_multitouch snd_usbmidi_lib joydev hid_generic usbhid
 snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd
_seq_midi snd_seq_midi_event snd_rawmidi eeepc_wmi snd_seq asus_wmi sparse_keymap snd_seq_device snd_timer x86_pkg_temp_thermal core
temp kvm_intel snd kvm crct10dif_pclmul crc32_pclmul ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 ghash_clmulni_intel xt_hl aesni_intel i9
15_bpo aes_x86_64 soundcore lrw gf128mul glue_helper ablk_helper cryptd serio_raw ip6t_rt intel_ips drm_kms_helper drm nf_conntrack_
ipv6 nf_defrag_ipv6 i2c_algo_bit 8250_fintek i2c_hid ipt_REJECT nf_reject_ipv4 hid shpchp mac_hid acpi_pad nf_log_ipv4 nf_log_common
 xt_LOG xt_limit xt_tcpudp xt_addrtype nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack ip6table_filter ip6_tables nf_conntrack_netbios
_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack iptable_filter ip_tables x_tables parport_pc ppdev lp par
port autofs4 btrfs xor raid6_pq mxm_wmi e1000e psmouse ptp pps_core ahci libahci wmi video
Oct 16 13:26:53 fozzy kernel: [ 6733.169337] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.19.0-30-generic #34-Ubuntu
Oct 16 13:26:53 fozzy kernel: [ 6733.169338] Hardware name: System manufacturer System Product Name/Z170-A, BIOS 1101 10/01/2015
Oct 16 13:26:53 fozzy kernel: [ 6733.169339]  ffffffffc07f3138 ffff880473c03d68 ffffffff817c4d5f 0000000000000007
Oct 16 13:26:53 fozzy kernel: [ 6733.169341]  ffff880473c03db8 ffff880473c03da8 ffffffff81076a8a ffff880473c03db8
Oct 16 13:26:53 fozzy kernel: [ 6733.169342]  ffff88045d711800 ffff88046043a000 ffff88045d7119a8 0000000000000000
Oct 16 13:26:53 fozzy kernel: [ 6733.169344] Call Trace:
Oct 16 13:26:53 fozzy kernel: [ 6733.169345]  <IRQ>  [<ffffffff817c4d5f>] dump_stack+0x45/0x57
Oct 16 13:26:53 fozzy kernel: [ 6733.169351]  [<ffffffff81076a8a>] warn_slowpath_common+0x8a/0xc0
Oct 16 13:26:53 fozzy kernel: [ 6733.169353]  [<ffffffff81076b06>] warn_slowpath_fmt+0x46/0x50
Oct 16 13:26:53 fozzy kernel: [ 6733.169366]  [<ffffffffc07982ec>] intel_check_page_flip+0x11c/0x130 [i915_bpo]
Oct 16 13:26:53 fozzy kernel: [ 6733.169376]  [<ffffffffc075f21e>] gen8_irq_handler+0x37e/0x5d0 [i915_bpo]
Oct 16 13:26:53 fozzy kernel: [ 6733.169378]  [<ffffffff810e030c>] ? __hrtimer_start_range_ns+0x2dc/0x410
Oct 16 13:26:53 fozzy kernel: [ 6733.169381]  [<ffffffff810cea87>] handle_irq_event_percpu+0x77/0x1a0
Oct 16 13:26:53 fozzy kernel: [ 6733.169382]  [<ffffffff810cebf1>] handle_irq_event+0x41/0x70
Oct 16 13:26:53 fozzy kernel: [ 6733.169385]  [<ffffffff810d1c5e>] handle_edge_irq+0x6e/0x120
Oct 16 13:26:53 fozzy kernel: [ 6733.169386]  [<ffffffff81017772>] handle_irq+0x22/0x40
Oct 16 13:26:53 fozzy kernel: [ 6733.169389]  [<ffffffff817cee1f>] do_IRQ+0x4f/0xf0
Oct 16 13:26:53 fozzy kernel: [ 6733.169390]  [<ffffffff817ccc2d>] common_interrupt+0x6d/0x6d
Oct 16 13:26:53 fozzy kernel: [ 6733.169391]  <EOI>  [<ffffffff81666525>] ? cpuidle_enter_state+0x65/0x160
Oct 16 13:26:53 fozzy kernel: [ 6733.169394]  [<ffffffff81666511>] ? cpuidle_enter_state+0x51/0x160
Oct 16 13:26:53 fozzy kernel: [ 6733.169396]  [<ffffffff81666707>] cpuidle_enter+0x17/0x20
Oct 16 13:26:53 fozzy kernel: [ 6733.169398]  [<ffffffff810b7d51>] cpu_startup_entry+0x311/0x3b0
Oct 16 13:26:53 fozzy kernel: [ 6733.169400]  [<ffffffff817b98b7>] rest_init+0x77/0x80
Oct 16 13:26:53 fozzy kernel: [ 6733.169403]  [<ffffffff81d4cfd3>] start_kernel+0x487/0x494
Oct 16 13:26:53 fozzy kernel: [ 6733.169405]  [<ffffffff81d4c120>] ? early_idt_handler_array+0x120/0x120
Oct 16 13:26:53 fozzy kernel: [ 6733.169407]  [<ffffffff81d4c4d7>] x86_64_start_reservations+0x2a/0x2c
Oct 16 13:26:53 fozzy kernel: [ 6733.169409]  [<ffffffff81d4c61c>] x86_64_start_kernel+0x143/0x152
Oct 16 13:26:53 fozzy kernel: [ 6733.169410] ---[ end trace 8305d2a3e3326e38 ]---

There is another message, too. Perhaps relevant.

Oct 17 11:16:52 fozzy kernel: [67722.891484] [drm:i915_hangcheck_elapsed [i915_bpo]] *ERROR* Hangcheck timer elapsed... render ring idle

 I am changing the status to Confirmed, as requested.