Setting up Windows on the second PC for reliable reads
The Windows settings that stop a dedicated second PC from dropping the card: USB selective suspend off, a power plan that never sleeps and one narrow Defender exclusion, on that machine only.
Short answer
On a second PC dedicated to the reader, disable USB selective suspend and sleep, and limit any Defender exclusion to the loader folder. Do not apply these settings to the game PC or any machine you use for banking, email or personal accounts.
On this page10
- Which machine are these settings for?
- What counts as a dedicated second PC?
- Why does the card disconnect when the PC is idle?
- How to set the power options on the second PC
- Setting USB suspend and sleep from the command line
- Why Defender quarantines the loader, and what to exclude
- How to add a single-folder Defender exclusion
- Keep these settings off the game PC and personal machines
- Is your second PC set up correctly?
- Common questions about second PC setup
Warning
Which machine are these settings for?
These settings are for a dedicated second PC, meaning a machine whose only job is to run the reader and talk to the card. Do not apply them to the gaming PC, or to a laptop or desktop you also use for banking, email, work, cloud accounts or purchases. The same goes for any machine that holds anything else you care about. The settings reduce power management and narrow one scanner's coverage, which is acceptable on a single-purpose tool machine but not on one that holds your personal life. If your second PC is also your everyday machine, stop here and either keep the defaults or get a separate machine.
What counts as a dedicated second PC?
Dedicated means a specific set of properties, not a general intention. The machine is not signed into your primary email, cloud storage or password manager, and it holds no documents you would miss. It is not used for purchases, and it has its own local account rather than a Microsoft account carrying your identity. If it is on your home network, the firewall stays on. Get the machine into that state first, because that state is what makes the other settings a reasonable trade rather than a bad idea.
Why does the card disconnect when the PC is idle?
USB selective suspend lets the hub driver power down a port it believes is idle. That is a sensible power saving for a keyboard, but for a DMA card it means a device that disappears while nobody is touching the machine. The result is the most confusing symptom in a new build: a link that works and then stops, with no change in between. Turning selective suspend off on the second PC is the highest-value change in this setup. On a machine plugged into mains power, it costs a trivial amount of energy.
How to set the power options on the second PC
Do all of these steps, because the most common half-fix is changing the power plan and skipping the per-hub checkbox.
- Open Control Panel, Power Options, and select a balanced or high performance plan rather than a battery saver plan
- Open Change plan settings, then Change advanced power settings
- Expand USB settings, then USB selective suspend setting, and set it to Disabled for every listed power state
- In the same dialog, set Sleep after, Hibernate after and Turn off hard disk after to Never
- Under PCI Express, set Link State Power Management to Off
- Open Device Manager, expand Universal Serial Bus controllers, and for every USB Root Hub and USB Hub entry open Properties, then Power Management. Clear the checkbox marked Allow the computer to turn off this device to save power
- Do the same for the FTDI or USB bridge device itself if it has a Power Management tab
- In Settings, System, Power, set Screen and sleep to never sleep while plugged in
- Reboot once, reconnect the card, and re-run your read test to confirm the link is stable over time
Setting USB suspend and sleep from the command line
Run these in an Administrator prompt on the SECOND PC. The GUIDs identify the standard USB settings subgroup and the USB selective suspend setting, and a value of 0 disables suspension. The last line prints the subgroup back so you can confirm that the change applied. These lines do not set the disk timeout, the PCI Express setting or the hub checkboxes, so do those with the steps above.
powercfg /setacvalueindex SCHEME_CURRENT 2a737441-1930-4402-8d77-b2bebba308a3 48e6b7a6-50f5-4782-a5d4-53bb8f07e226 0
powercfg /setdcvalueindex SCHEME_CURRENT 2a737441-1930-4402-8d77-b2bebba308a3 48e6b7a6-50f5-4782-a5d4-53bb8f07e226 0
powercfg /change standby-timeout-ac 0
powercfg /change hibernate-timeout-ac 0
powercfg /setactive SCHEME_CURRENT
powercfg /query SCHEME_CURRENT 2a737441-1930-4402-8d77-b2bebba308a3Why Defender quarantines the loader, and what to exclude
Loaders are packed and self-modifying, which is also what malware looks like, so Windows Defender frequently quarantines them on sight. On a dedicated tool machine, the correct response is a folder exclusion for the loader directory: one specific path and nothing wider. Keep real-time protection enabled, do not exclude a whole drive or your downloads folder, and do not turn protection off as a shortcut. Understand what you are accepting: files in an excluded folder are not scanned, so anything you put there goes unexamined. That trade is only defensible when the folder's contents come from a source you have decided to trust and the machine holds nothing.
How to add a single-folder Defender exclusion
Exclude one folder on the second PC, and leave real-time protection on everywhere else.
- Create a single dedicated folder for the loader, at a short path you will remember
- Open Windows Security, then Virus and threat protection
- Under Virus and threat protection settings, choose Manage settings
- Confirm Real-time protection is ON and leave it on
- Scroll to Exclusions, choose Add or remove exclusions, then Add an exclusion, then Folder
- Select only that one loader folder
- Put nothing else in that folder, not even downloads, archives or unrelated tools
- Review the exclusion list every few months and remove entries you no longer use
Warning
Keep these settings off the game PC and personal machines
People get this part wrong, and it is the part that causes real damage. Do not disable protections on the gaming PC, because it runs an anti-cheat that expects a normal system and weakening it does not help you anyway. Do not copy these settings onto a laptop you use for work, banking or personal accounts. Do not present them to anyone as general advice to switch off antivirus, because that is not what they are. The whole argument rests on the machine being single-purpose and holding nothing of value, and without that premise the advice is simply bad.
Is your second PC set up correctly?
- The machine is single-purpose and signed into no personal accounts
- USB selective suspend is disabled in the active power plan, on AC and on battery
- Every USB Root Hub and USB Hub has its power-saving checkbox cleared
- Sleep, hibernate and disk timeouts are set to never while plugged in
- PCI Express link state power management is off
- Real-time protection is ON, with exactly one folder excluded
- Windows firewall is on
- None of these settings has been applied to the game PC or to any machine you use personally
Common questions about second PC setup
Should I disable Windows Defender on the second PC?
No. Leave real-time protection on and exclude the one loader folder. Disabling protection completely gains you nothing over a scoped exclusion and leaves the machine with no protection at all.
Can I do any of this on my gaming PC?
No, because the game PC runs an anti-cheat that expects an ordinary, protected system. It is usually a machine you also use normally, so none of these settings belong there.
Why does my card disconnect when I step away from the PC?
The cause is USB selective suspend, or a USB Root Hub that is still allowed to power down. Disable selective suspend in the power plan and clear the power-saving checkbox on every hub, because you need both changes, not one.
Is a debloating script a good idea?
Generally no. Scripts that strip Windows services remove things the USB stack, the runtimes or Windows Update depend on, which leaves you debugging two problems. A clean install plus these specific settings is the safer route.
Does any of this affect detection risk?
No, and do not treat it as if it does. These settings keep a USB link stable and stop a scanner quarantining a file. Detection risk comes from firmware quality, configuration and how you play, and no Windows setting removes it.
Should the second PC have internet access?
Usually yes, because licence checks and updates need it and the clock needs time sync. Keep the firewall on, and keep the machine signed out of your personal accounts.
Sources
These are the settings the team applies to its own second PCs, and each one is on the list because cards kept dropping until it was changed.
Read next
- USB topology for DMA: controllers, hubs and ports
- Using a laptop as the second PC
- Windows versions and builds: what breaks and when
- How to set up a second PC for DMA
- Clean Windows before a spoofer
- Secure Boot: what it does and what turning it off costs
- How a wrong system clock breaks TLS and licence checks
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