Update: Luckily I was wrong. The board is ok. But my Pico-PSU is defect. I don't seem to have much luck with my PSUs these days... :P
I found an old 200W ATX PSU, which works.
m3x is right, U-Boot 1.3.1 behaves nicely and defaults to serial.
Although it doesn't like my GeForce 6200LE, and hangs after VESA is detected as being ok:
U-Boot 1.3.1e (Jul 5 2012 - 19:02:53)
CPU: AMCC PowerPC 440EP Rev. C at 666.666 MHz (PLB=133, OPB=66, EBC=66 MHz)
I2C boot EEPROM enabled
Bootstrap Option H - Boot ROM Location I2C (Addr 0x52)
Internal PCI arbiter enabled, PCI async ext clock used
32 kB I-Cache 32 kB D-Cache
Board: Sam440ep-flex
I2C: ready
DRAM: 1024 MB
PCI: Bus Dev VenId DevId Class Int
01 04 1013 6005 0401 00
01 05 1033 0035 0c03 00
01 05 1033 0035 0c03 00
01 05 1033 00e0 0c03 00
00 0a 12d8 8150 0604 00
00 0c 10de 0221 0300 00
00 0e 1095 3114 0180 00
In: serial
Out: serial
Err: serial
Net: ppc_4xx_eth0, ppc_4xx_eth1
SM502: not found
VGA: 1
VESA: OK
Doesn't u-boot support all graphics cards in VESA-mode? Is there a list of working cards somewhere?
Without graphics card I can use u-boot:
U-Boot 1.3.1e (Jul 5 2012 - 19:02:53)
CPU: AMCC PowerPC 440EP Rev. C at 666.666 MHz (PLB=133, OPB=66, EBC=66 MHz)
I2C boot EEPROM enabled
Bootstrap Option H - Boot ROM Location I2C (Addr 0x52)
Internal PCI arbiter enabled, PCI async ext clock used
32 kB I-Cache 32 kB D-Cache
Board: Sam440ep-flex
I2C: ready
DRAM: 1024 MB
PCI: Bus Dev VenId DevId Class Int
01 04 1013 6005 0401 00
01 05 1033 0035 0c03 00
01 05 1033 0035 0c03 00
01 05 1033 00e0 0c03 00
00 0a 12d8 8150 0604 00
00 0e 1095 3114 0180 00
In: serial
Out: serial
Err: serial
Net: ppc_4xx_eth0, ppc_4xx_eth1
SM502: not found
VGA: NO CARDS
USB: OHCI pci controller (1033, 0035) found @(1:5:0)
scanning bus for devices... 1 USB Device(s) found
Last Switch off: m41st84 RTC Clock stopped!!!
Date: 2265-25-45 (unknown day) Time: 45:85:85
IDE Device 0: not available
AOS4 FLB
FLB: no SLB found in any of the designated boot sources; returning to u-boot.
Press any key to continue
Now I need to find a PSU which can replace the 400W model in my new micro-ATX tower...