Assembly

First boot and BIOS setup

What to do once the case is closed: the memory profile, boot order, and the settings genuinely worth changing.

2 min readBeginner20 minUpdated August 1, 2026

Step 1 of 3
The first power-on
5 min
Connect the monitor to the graphics card, not to the motherboard output. That is the single most common cause of a black screen on first boot in a system with a discrete card.
Flip the switch at the back of the PSU, then press the case power button. The first start takes longer than later ones — the board is training the memory configuration, which on DDR5 can take up to a minute with a dark screen.
If there is no picture after two minutes, cut the power and move to the no-display troubleshooting guide. Do not leave the machine sitting in that state.
Step 2 of 3
Enabling the memory profile
5 min
Enter the BIOS with Delete or F2 immediately after powering on. Find the setting called EXPO on AMD boards or XMP on Intel boards.
Select the first profile, save and restart. After the reboot, check in Windows Task Manager that the memory reports its rated frequency.
If the machine will not start with the profile enabled, clear the BIOS with the jumper or button on the board and try the second profile if one is offered. Instability with a rated profile does happen and does not mean the memory is faulty.
Important
Without enabling the profile, memory runs at its base frequency, far below the figure on the box. This is the one setting you must change in every new build.
Step 3 of 3
The fan curve
10 min
Default curves are set conservatively and are usually too aggressive — the fans ramp on every brief temperature spike, which you hear as constant surging.
A sensible starting point: quiet up to 60 degrees, a smooth ramp between 60 and 80, full speed above 85. Also set a response delay of a few seconds so short spikes do not spin the fans up.
Make these changes in the BIOS rather than in desktop software. BIOS settings apply from the moment the machine starts and do not depend on an application having loaded.

Community opinions

„Half the "it will not boot" posts come down to badly seated memory or a monitor plugged into the board instead of the card. Always check those two first.”
techsupport_veteran · r/techsupport

Building a PC step by step
A complete walkthrough from unboxing to first boot. Order matters — the sequence here saves a lot of backtracking.
The computer will not start — diagnostics
An ordered list of causes from most to least common. In most cases the problem is in the first three entries.

Back to Guides

First boot and BIOS setup

The first power-on

Enabling the memory profile

The fan curve

Community opinions

Related guides

Building a PC step by step

The computer will not start — diagnostics