MP 1,1-5,1 Mac Pro 3.1 no boot after CPU upgrade

[SaroK]

Hello guys, its my first time in the forum but I have searched for this problem endlessly to no avail.

I recently purchased a pair of Xeon X5460s, upgrading from a single 2.8 Ghz, the RAM in my system is 32Gb 667 which I have checked is compatible with these new CPUs.

When switching on, all fans run normally as do all my drives, no error LEDs show up either on the board.

There is however no boot chime nor any other indication that things are fine, tried various ways to boot, switched CPUs and heatsinks numerous times as well. I have also attempted NVRAM and SMC resets which also haven’t worked.

The only thing I can guess is that i may need to flash the BIOS?

I do notice one thing that wasn’t there before the new CPU’s, the disk drive makes a little whirring noise every few seconds, not sure how related that can be.

Any help or past experience with such an Issue would be extremely appreciated! Thanks guys

Update- I have left the Mac running, now on one of the ram boards, the DIMM 4 LED is flashing, is there any diagnostics for that?

 

[Snow Tiger]

what's the S-spec version of your upgrade processors ? If you don't know , upload a picture of both your silicon . They must match and also be the compatible version .

If a failing DIMM is causing an aborted boot sequence , place matching memory modules in the DIMM slots number 1 of both your memory risers . Leave all the other slots unpopulated . solid red LEDs on the memory risers is an indication of a failed module - this often happens with DDR2 modules as they suffer from thermal fatigue .

 

[SaroK]

what's the S-spec version of your upgrade processors ? If you don't know , upload a picture of both your silicon . They must match and also be the compatible version .

If a failing DIMM is causing an aborted boot sequence , place matching memory modules in the DIMM slots number 1 of both your memory risers . Leave all the other slots unpopulated . solid red LEDs on the memory risers is an indication of a failed module - this often happens with DDR2 modules as they suffer from thermal fatigue .

The new CPUs I purchased are both SLANP, the CPU originally in the board was SLANT. On another post I noticed that my old cpu supported 800 ram modules even though my system has 667s which I why I purchased the X5460s as they’re compatible with 667, the previous CPU did function normally.

I will give what you have mentioned a go and see where that takes me, thank you!

 

[Snow Tiger]

The new CPUs I purchased are both SLANP, the CPU originally in the board was SLANT. On another post I noticed that my old cpu supported 800 ram modules even though my system has 667s which I why I purchased the X5460s as they’re compatible with 667, the previous CPU did function normally.

I will give what you have mentioned a go and see where that takes me, thank you!

I would not worry about the speed of the memory modules in the Mac Pro 3,1 ( 2008 ) . Regardless of installed processor , 667 MHz and 800 MHz are both compatible . The modules may downscale their performance ( e.g. 800 MHz modules may run at 667 MHz ) depending on support from the processor , but they will work if they meet all the other requirements .

 

[SaroK]

I would not worry about the speed of the memory modules in the Mac Pro 3,1 ( 2008 ) . Regardless of installed processor , 667 MHz and 800 MHz are both compatible . The modules may downscale their performance ( e.g. 800 MHz modules may run at 667 MHz ) depending on support from the processor , but they will work if they meet all the other requirements .

So I removed all modules except those in DIMM1, no more LED flashes on the RAM boards, but I so get ERRB LED Flashing which from what I recall is to do with the upper CPU, would it be a heat sink issue or something worse with the processor? Thanks

 

[Snow Tiger]

From the horse's mouth on ERRB LED light being on :

LED 3 CPU B (Lower Processor) Error LED 4 CPU A (Upper Processor) Error
Normally off. These LEDs come on if an error occurs or if the BootROM is corrupted. They do not depend on the DIAG_LED button being pressed.
Related symptoms include no video or the computer is hung up. If the BootROM is corrupted, the optical drive tray should eject, prompting for the insertion of a recovery disc to restore the BootROM.
Troubleshooting:
• With the computer booted, up press the SYS_RST switch. If this clears the CPU Error LED,
check for incompatible device driver software that may have been installed for added
hardware.
• If the Error LED is still on, power down the computer and try resetting the SMC. Restart the
computer.
• Reset the power supply by unplugging the AC cord for 10 seconds.
• Unplug AC cord and remove any added DIMMs and PCI Express cards. If this causes the
LED to go off, repopulate the DIMMs and/or PCI Express cards to find the combination that caused the LED to come on. Overheated memory could be a possible cause for this CPU error LED to come on. Check fan operation.
• Unplug the AC cord and remove the battery for 10 seconds. You may need to remove a PCI Express card to get to the battery. Reinstall the battery and restart the computer.
• Try swapping CPU A and CPU B locations. If the CPU Error LED follows the CPU, replace that CPU.
• Try replacing the logic board.