On a Lenovo G70-70 I encounter nearly the same problem. Sometimes the laptop enters a state where the screen gets black every 12-13 seconds. Sometimes a suspend (close/open lid) helps, often it does not. Sometimes the system recovers without any intervention.

dmesg output:

[20896.033375] ------------[ cut here ]------------
[20896.033416] WARNING: CPU: 1 PID: 4401 at /build/linux-OdodyZ/linux-3.19.0/drivers/gpu/drm/i915/intel_display.c:7831 hsw_enable_pc8+0x633/0x640 [i915]()
[20896.033419] PCH PWM1 enabled
[20896.033421] Modules linked in: ctr ccm rfcomm bnep bbswitch(OE) nls_iso8859_1 rtsx_usb_ms memstick arc4 intel_rapl uvcvideo ath9k ath9k_common ath9k_hw videobuf2_vmalloc iosf_mbi videobuf2_memops x86_pkg_temp_thermal videobuf2_core intel_powerclamp v4l2_common ath mac80211 videodev coretemp snd_hda_codec_conexant media cfg80211 kvm snd_hda_codec_hdmi snd_hda_codec_generic snd_soc_rt5640 snd_hda_intel snd_soc_rl6231 snd_soc_core snd_hda_controller i915 snd_hda_codec crct10dif_pclmul crc32_pclmul snd_compress ghash_clmulni_intel snd_pcm_dmaengine snd_hwdep aesni_intel aes_x86_64 snd_pcm lrw snd_seq_midi gf128mul ath3k snd_seq_midi_event glue_helper ablk_helper btusb snd_rawmidi cryptd drm_kms_helper snd_seq drm mei_me snd_seq_device snd_timer bluetooth joydev mei snd serio_raw dw_dmac ideapad_laptop
[20896.033492]  soundcore dw_dmac_core snd_soc_sst_acpi sparse_keymap shpchp 8250_fintek i2c_hid i2c_algo_bit 8250_dw video i2c_designware_platform i2c_designware_core lpc_ich soc_button_array spi_pxa2xx_platform mac_hid wmi parport_pc ppdev lp parport autofs4 rtsx_usb_sdmmc rtsx_usb hid_generic usbhid hid psmouse ahci r8169 libahci mii sdhci_acpi sdhci
[20896.033529] CPU: 1 PID: 4401 Comm: kworker/1:2 Tainted: G        W  OE  3.19.0-25-generic #26-Ubuntu
[20896.033532] Hardware name: LENOVO 80HW/Lenovo G70-70, BIOS B6CN15WW 04/23/2015
[20896.033539] Workqueue: pm pm_runtime_work
[20896.033542]  ffffffffc055f310 ffff880212bf3b98 ffffffff817c4518 0000000000000007
[20896.033548]  ffff880212bf3be8 ffff880212bf3bd8 ffffffff81076a6a 00000001004e83a4
[20896.033554]  ffff880243030000 ffff8800a9b44b80 ffff8800a9b44b90 ffff8800a9b44800
[20896.033560] Call Trace:
[20896.033569]  [<ffffffff817c4518>] dump_stack+0x45/0x57
[20896.033575]  [<ffffffff81076a6a>] warn_slowpath_common+0x8a/0xc0
[20896.033581]  [<ffffffff81076ae6>] warn_slowpath_fmt+0x46/0x50
[20896.033627]  [<ffffffffc0509da3>] hsw_enable_pc8+0x633/0x640 [i915]
[20896.033649]  [<ffffffffc049cff0>] intel_suspend_complete+0xf0/0x6c0 [i915]
[20896.033670]  [<ffffffffc049d844>] intel_runtime_suspend+0xc4/0x230 [i915]
[20896.033677]  [<ffffffff814026f0>] ? pci_legacy_suspend_late+0xf0/0xf0
[20896.033684]  [<ffffffff8140274f>] pci_pm_runtime_suspend+0x5f/0x150
[20896.033689]  [<ffffffff814026f0>] ? pci_legacy_suspend_late+0xf0/0xf0
[20896.033696]  [<ffffffff81511e26>] __rpm_callback+0x36/0xd0
[20896.033702]  [<ffffffff81511ee8>] rpm_callback+0x28/0x90
[20896.033709]  [<ffffffff81512061>] rpm_suspend+0x111/0x630
[20896.033717]  [<ffffffff810ae94f>] ? put_prev_task_fair+0x2f/0x50
[20896.033724]  [<ffffffff8151382a>] pm_runtime_work+0xba/0xf0
[20896.033730]  [<ffffffff8108fd58>] process_one_work+0x158/0x430
[20896.033736]  [<ffffffff8109089b>] worker_thread+0x5b/0x530
[20896.033743]  [<ffffffff81090840>] ? rescuer_thread+0x3a0/0x3a0
[20896.033750]  [<ffffffff81095939>] kthread+0xc9/0xe0
[20896.033758]  [<ffffffff81095870>] ? kthread_create_on_node+0x1c0/0x1c0
[20896.033763]  [<ffffffff817cb518>] ret_from_fork+0x58/0x90
[20896.033771]  [<ffffffff81095870>] ? kthread_create_on_node+0x1c0/0x1c0
[20896.033775] ---[ end trace b77ad5f7cd9dcefd ]---