Long story short:
For reference, the components are as follows:
Old motherboard - ASUS P4SP-MX (socket 470, 20 pin ATX)
Old PSU - no brand 300W (20 pin ATX)
Old graphics card - Geforce 6800GT AGP
New graphics card - Radeon 3850 AGP
New PSU - Revoltec Chromus II (RPS-500V2, 24 pin ATX)
24 pin to 20 pin ATX adapter
Any idea why this system will not boot with a more modern PSU despite the adapter which was designed for this exact scenario? Although the PSU is probably not that well known, it is a very solid modular unit with high quality components and has served us for maybe 4 years now, running 24/7.
- I upgrade the graphics in my ancient media pc and find it needs more power than the cheap PSU can supply.
- I borrow a PSU with plenty of power and solid rails from another machine and find I need to use a 24 pin to 20 pin ATX adapter as the motherboard is so old and the extra 4 pins on the PSU do not detach like a lot of models.
- Once installed correctly, the system will not POST with this PSU. Fans on all units spin up as does the HDD, lights are on in the right places but no beep and no picture. I can't turn it off by tapping the power button so I have to hold it in for 4 seconds, suggesting to me the system is in some sort of 'hung' state.
- I verify that it's not the new graphics card requiring even more power. To do this I install the old one and get the same problem.
- I install the original PSU and the system boots once again.
- Although not necessary, I confirm that the bigger PSU has enough power for the new graphics card by putting them both in another system and it boots fine.
For reference, the components are as follows:
Old motherboard - ASUS P4SP-MX (socket 470, 20 pin ATX)
Old PSU - no brand 300W (20 pin ATX)
Old graphics card - Geforce 6800GT AGP
New graphics card - Radeon 3850 AGP
New PSU - Revoltec Chromus II (RPS-500V2, 24 pin ATX)
24 pin to 20 pin ATX adapter
Any idea why this system will not boot with a more modern PSU despite the adapter which was designed for this exact scenario? Although the PSU is probably not that well known, it is a very solid modular unit with high quality components and has served us for maybe 4 years now, running 24/7.