MacPro 4,1 powers on, but no response....... advice welcomed

Hello,

My MacPro4,1 running Mavericks was working fine then suddenly the three monitors went blank and the computer was unresponsive. I restarted and it took a while to boot, but eventually came back to life. Around two hr later the screens froze and once again completely unresponsive. This time when I tried to reboot the powerlight, the CPU and graphics fans came on, but nothing else.

I removed the startup drive and installed it in another MacPro (5,1) I have and ran disk utilities. It found some errors on the drive's catalog, which it fixed. I reinstalled the start up drive in the 4,1 and tried to boot, but as before, the powerlight and fans came on but nothing else.

So far I've tried the following.
1. Swapped the OWC RAM with the original Samsung RAM that came with the 4,1 - that didn't fix it.
2. Replaced the two ATI Radeon graphics cards with the Sapphire card from my 5,1 - that didn't fix it.

Any advice for further trouble shooting gratefully received. I'm wondering if the logic board might be shot......

Thanks.

gmacg

I'm thinking hardware, and the first possibility is always power supply (yes, even with fans and power light).

I don't know if it's helpful, but when I boot up and shut down the 4,1 via the power button on the front of the case, (with the case open), I noticed a red LED that lights up both at power on and power off. Does anyone know if this is normal, or if it is a trouble light that might be indicating a hardware issue ?

Anyone got any reliable way to test the PS ? Can I use the output at one of the connectors or is that an unreliable way to test it ?

Thanks again.

I agree that the power supply might be failing. The only way to test it is to swap it out with a known good one. Check eBay to see if you can pick one up at a decent price.

gmacg said:

Anyone got any reliable way to test the PS ?

Click to expand...

The best way is as chscag mentioned...swap the current one for a known good one.

But...another way you could test what you have in the meantime...is lesson the "load" on the current power supply. To do this I would suggest only installing one video card...and only running one monitor. If you still had the original GT-120 video card...installing it might even be better since it's a pretty low power card.

Also just run one HD (in case you have multiple installed).

HTH,

- Nick