Hi together,

I am trying to bring back an old Dell Dimension XPS R450 to live, but I cannot make it boot. As far as I remember it was put aside in working condition 20 years ago.

Hardware: Pentium ii 450 MHz, Dell-Version of Intel SE440BX mainboard

Symptoms

• No beep when it boots, it is stuck at the vendor splash screen. If I hit F2 during boot, I can see the attached screen.
• Keyboard is initialized and F2 during boot is recognized, but then unresponsive. Num or caps lock for example cannot be toggled. Tried different keyboards already.
• In recovery mode (CMOS jumper removed) I can boot from a floppy and the BIOS is updated from the floppy.

Already tried

• Removed all extension cards, drives, etc. and checked board for obvious scratches or damages, cleaned everything - nothing
• Upgraded BIOS in recovery mode. There is no difference in behaviour between the original P09 Dell BIOS and the Intel P12 BIOS which I flashed recently
• POST card shows many codes during startup, then some seconds 52 55 and then forever 50 4E. 50 and 4E mean "Display copyright message" and "Display CPU type and speed" and it looks like CPU type and speed are not displayed, so this seems to be where it hangs
• I tried two pentium 2 CPUs (original passively cooled 450MHz and one actively cooled 400MHz) with no difference
• I tried several RAM modules in all slots - no difference. If I do not put a module, then I get the missing RAM beeps.
• I tried different graphics cards - no change
• 2.0V CPU voltage is measured to be fine, no ripples (checked with scope)
• All ATX voltages are present and in tolerances, no ripples
• No excessively hot chip on the mainboard, checked with thermal camera.
• Caps look fine in the power supply and on the board, and since I do not see any ripples I think there is no supply issue
• Resoldered CPU slot soldering joints from the bottom because I thought one of them could have broken (most mechanical load due to heavy CPU), but did not change anything

Questions

• I have read there could be an issue with the BIOS EEPROM chip Intel E28F002 being corrupted or faulty. However, if I can flash a new BIOS and the chip is not getting warm, is that realistic?
• If there is an issue with the CPU, how can it show the splash screen and upgrade the BIOS?
• Any ideas what else I can do? Why should it hang at Code 50?

many thanks in advance!