Dell OptiPlex GX520 & GX620: CPU Upgrade to P4 and Pentium D

[shulfe]

When system halted with D820 (not D830) after reboot - any messages on the screen?

No, there was no sign BIOS boot. If press ctrl alt del until all BIOS cheks done (loading bar) system reboot, halt and FAN takes max rpm.  

Do D915, D930 and D945 work with native BIOS

With native BIOS allert message, after reboot unsure, I will take experiment again.

[DeathBringer]

Please disable Quiet Boot in BIOS and you can see text messages instead of loading bar.
Post a foto of the screen when system is halted after reboot.
Do D915, D930 and D945 reboot normally with my first mod?

[shulfe]

I take few experiments. Plug ps/2 keyboard, unplug all USB. Firtst five or six times its reboot normal, then 50/50, then in 99% halt. When halt no signal to mon in all times. When take changes in system config (memory for example) first time it may reboot normal.Then I take another GX520 with same revision, try it with D830. In A7 bios it works (with message) windows boot normal, reboot all time good, update to A11 mod2 and.. it work. I dont know why some PC work and another not, may be power supply bad. I will try all 8 GX520 i have and post result.

[DeathBringer]

Good news. I think it's a problem with bad capacitor on one motherboard. All experiments confirm this supposition.
Can you try last experiment? Please flash first mod (not mod2) into good motherboard and check it. I think my mod2 is useless.

[shulfe]

OK. First GX520 i update with celeronD second with D830, could it affect?

[DeathBringer]

Motherboard in first GX520 may halt randomly with any CPU. So you can try CPU with low power.