[SOLVED]H170 boot issue when CSM is disabled
Printed From: ASRock.com
Category: Technical Support
Forum Name: Intel Motherboards
Forum Description: Question about ASRock Intel Motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=6488
Printed Date: 30 Jul 2025 at 12:58pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: [SOLVED]H170 boot issue when CSM is disabled
Posted By: keeka
Subject: [SOLVED]H170 boot issue when CSM is disabled
Date Posted: 03 Nov 2017 at 11:53pm
Hi
I am trying to boot with CSM disabled. Motivations and what I am experiencing are similar to OP in this http://forum.asrock.com/forum_posts.asp%3FTID=2293&title=z97eitx-ac-compatibility-support-module-issues" rel="nofollow - post .
I can disable CSM and then successfully restart and also boot from cold. However, if I leave the machine for any length of time (hours, over night say), then when I cold boot, I get 5 beeps (AIUI this means failure to init video). The machine then restarts of its own accord, having re-nabled CSM itself. All other UEFI/BIOS customisations seemed to be preserved.
I would like to have CSM off as I have discovered that, without it, my displayport monitor switches on immediately and I can see boot managers etc with out resetting the machine straight after a cold boot. Plus, it would be good to go pure UEFI as I do not appear to need legacy/BIOS support.
I am sure the installed OS are UEFI mode and the graphics (which the beeps indicate are the culprit) should have a GOP VBIOS provided in the ASROCK UEFI for this board:
Asrock H170M PRO4
BIOS 7.1
CPU i5-6600
No discrete graphics in use, I have BIOS set to init built in IGPU first.
Advice and suggestions much appreciated.
Many thanks.
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Replies:
Posted By: keeka
Date Posted: 04 Nov 2017 at 2:36pm
Seems the monitor must be powered up when the PC boots in UEFI mode (CSM disabled).
I use an APC BACK-UPS, which cuts power to the peripherals when the PC switches off. Seems that the monitor is not quite ready in time, when the PC boots, for the video BIOS to consider the monitor available over DPP. I have plugged the monitor in to a mains socket independent of the UPS's and the machine boots fine.
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