BIOS has forgotten everything like USB
you need a old keyboard to set you up first

#! How to Do A Resetting of Dell Dimension XPS T800R to Boot Windows

then the Delete on startup will open the

Dell Dimension XPS T800R Setup

in setup

# !Main
Processor Serial Number [Disabled]
L2 Cache ECC Support [Auto]

System Time: [00.00.15] set to right time it in 24 hour,, for
(00:00:00 to 11:59:59 is AM) & (12:00:00 to 23:59:59 is PM)
System Date: [09/12/2010]

# !Advanced
Plug & Play O/S: [Yes]
Reset Configuration Data: [No]

NumLock: [Auto]

Peripheral Configuration
IDE Configuration
Diskette Options
DMI Event Logging
Resource Configuration

# !Do Resource Configuration first

# !Do Peripheral Configuration
Serial Port A: [Enabled]
Base I/O address: [COM 1]
Interrupt: [IRQ 4]
Parallel Port: [Auto]
Mode: [Output Only]

Legacy USB Support: [Enabled]
## !Now that USB Keyboard will work LOOL ##

Esc
#! Press Esc to Exit Menu

# !Do IDE Configuration

IDE Controller: [Both]

Primary IDE Master [Auto]
Primary IDE Slave [Auto]
Secondary IDE Master [Auto]
Secondary IDE Slave [Auto]

## ! you can set all to Auto here.
## If it say [None] click it and set it to
## Type: [Auto]
## Press Esc to Exit Menu

IDE Configuration
Press Esc to Exit Menu

# !Do Diskette Options

Diskette Controller: [Enabled]

Diskette A: [1.44/1.25 MB 3 1/2"]

Diskette Write Protect: [Disabled]

Press Esc to Exit Menu

#! on Manu at top click Boot

Boot-time Diagnostic Screen [Enabled]
QuickBoot Mode: [Disabled]

Restore On AC/Power Loss: [Stay off]
On LAN: [Stay off]

First Boot Device [Removable Devices]
Second Boot Device [ATAPI CD-ROM Driv]
Third Boot Device [Hard Drive]
Fourth Boot Device [Network Boot]

Hard Drive
Removable Devices

# ! We do Hard Drive
#! The Bootable Add-in Card have to be on 1. and Primary IDE Master Hard
Drive on 2.

1. [Bootable Add-in Card]
2.[]
3.[]

#! My is 2.[WDC WD-200AB-00CM0-{PM}] your name of your Primary IDE Master
not the some
#! My is 3.[ST320011A-{PS}] your name of your Primary IDE Slave if you have
one
#! Yours may look like this and its OK

1. [Bootable Add-in Card]
2.[]
#! Read the Item Specific Help on the right side of page
#! Press Esc to Exit Menu

# ! We do Removable Devices

1.[Legacy Floppy Drives]

#! Press Esc to Exit Menu
#! Now on the top Menu Click Exit
#! A POP-UP

Setup Confirmation

Save configuration changes and exit now?
[Yes]
Enter
Accept

#! When you see the Dell logo on the right side
#! Power off
#! unplug that old Keyboard and Plug that USB KeyBoard
#`! Power ON Test is BY doing {{{ Ctrl - Delete }}} if it ReBoots you good
to go