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Item#: N82E16815158254

StarTech 2 Port Native PCI Express RS232 Serial Adapter Card with 16550 UART Model PEX2S553

  • PCI Express to Serial Port Card
  • 460.8 Kbps Data Transfer Rate
  • External Ports 2 x Serial Ports
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The PEX2S553 PCI Express serial card lets you turn a PCI Express slot into 2 RS232 (DB9) serial ports. Based on a native single chip design (no bridge chip), this 2-port serial adapter card allows you to harness the full capability offered by PCI Express (PCIe), and reducing the load applied to the CPU by as much as 48% over conventional serial cards.

The RS232 Serial Adapter Card (PEX2S553) is compatible with a broad range of operating systems including Windows 2000/XP/2003/Vista/Windows 7/Server 2008 R2 (32 and 64 bit), Linux Kernel 2.6.11 and up, and MAC OS 10.4 and above.

Plus, the serial card includes an optional half-height/low profile bracket that allows the card to be installed in any PCI Express slot, regardless of the size of the computer case.

  • newegg Add Two Serial Ports to Your PC Based on the native single-chip, single lane PCI Express chipset, the StarTech PEX2S553 card adds two RS232 (DB9) Serial ports to any PCIe equipped computer for easy connection to serial devices.
  • newegg Low Profile Bracket Included Standard and low profile/half-height brackets are included to ensure fitment in any system.

Learn more about the STARTECH PEX2S553




PCI Express to Serial Port Card
External Ports
2 x Serial Ports
Data Transfer Rate
460.8 Kbps
Operating Systems Supported
DOS, Windows 95/ 98SE/ 2000/ XP(32/64bit)/ Server 2003(32/64bit)/ Vista(32/64bit)/ 7(32/64bit)/ Server 2008 R2, Linux, and Mac OS 10.4.x and up
Windows XP Embedded/ POS Ready 2009/ Embedded System 2009 OS/ CE 5.0/ CE 6.0


Two high speed RS232 serial ports with support for data transfer rates up to 460.8 Kbps
Compliant with PCI Express base specifications revision 1.0a
Includes half-height/low profile mounting bracket
Selectable power output on pin 9 for the serial port
128-byte deep FIFO per transmitter and receiver
Native single-Chip, single lane PCI Express
Automated out-of-band flow control using CTS/RTS and DSR/DTR
Automated in-band software flow control using programmable Xon/Xoff in both directions

Manufacturer Warranty

1 year limited
1 year limited

Quick Info


  • Limited Warranty period (parts): 1 year
  • Limited Warranty period (labor): 1 year

Customer Reviews of the STARTECH PEX2S553

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  • Peter B.
  • 12/9/2013 7:02:11 PM
  • Tech Level: Somewhat High
  • Ownership: 1 month to 1 year

2 out of 5 eggsDoes Not Work in Windows 7 Pro 64-bit

Pros: We have used this serial card in many PCs using Windows XP Pro as well as Windows 7 Pro -- both 32-bit. Has both full profile and low profile brackets in same box.

Cons: This card does not work properly in Windows 7 Pro 64-bit mode. The card goes dormant after 15 minutes. We use a key reading device with its own memory resident software. When the card goes dormant, the key reading device stops working. If you terminate the software and use the DOS command mode, the serial port will respond to you. Re-loading the software afterwards does not let the device work though. The PC has to be restarted. Ended up pulling these serial cards and using a serial port adapter cable from the PC manufacturer.

Other Thoughts: Did speak to StarTech technical support but they wanted loopback tests done -- we didn't have anything to do that with. The PC manufacturer sent us a serial comm port adapter cable to connect to the motherboard and allow for a serial comm port interface on the case. This worked fine. Never had a problem afterwards with the serial port going dormant.

1 out of 1 people found this review helpful. Did you? Yes No

  • 8/30/2011 12:01:09 PM
  • Tech Level: Somewhat High
  • Ownership: 1 week to 1 month
  • Verified Owner

3 out of 5 eggsInfant Mortality

Pros: I am giving this three eggs because this card was easy to install, supported by older and current OSs and their technical support was surprisingly easy to access and helpful - confirm using the latest driver, re-seat the card, try a different PCI-e slot/computer, get another card.

Cons: I am not giving it five eggs because it only worked for two days before starting to fail - it would drift in and out of being recognized by Windows XP and eventually was unresponsive after about a week.

Other Thoughts: Now it is up to Newegg's RMA process to get a replacement and see how it performs.

1 out of 1 people found this review helpful. Did you? Yes No

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Home > 
Computer Hardware > 
Computer Accessories > 
Add-On Cards > 
Item#: N82E16815158254
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