MP 1.1 possible defect

[Macstefws]

Peers,

Got my self a second used MP 1.1 w/2x2.66GHz E51xx series today, which when powered on, just stays black screened. Fans starts, diagnostic LED for CPUB went red. So I pulled out CPU B, this turned off the LED, but no more than this. Pushing diagnostic switch makes power LED go green, first LED flash yellow and GPU flashing green, tried SMC RST also no difference.

Should I be able to boot with only one CPU in my MP?

Any hints are welcome on possible cause, Thanks!

 

[hackerwayne]

Peers,

Got my self a second used MP 1.1 w/2x2.66GHz E51xx series today, which when powered on, just stays black screened. Fans starts, diagnostic LED for CPUB went red. So I pulled out CPU B, this turned off the LED, but no more than this. Pushing diagnostic switch makes power LED go green, first LED flash yellow and GPU flashing green, tried SMC RST also no difference.

Should I be able to boot with only one CPU in my MP?

Any hints are welcome on possible cause, Thanks!

CPU Diag. LED lights up does not always mean a CPU defect. It can caused by a few things.

1. A short circuit, this happened to me before, check the DVD drive area, remove both DVD drive and try to boot the system

2. CPU overheat, check if theres sufficient thermal paste on the CPU

3. If the CPU was upgraded/replaced, make sure they are compatible

You can boot with 1 processor but you can only have RAM sticks on Riser A, more then that, the system will refuse to boot.

Quoted from Apple Support Site
"Verify trickle power
Diagnostic LED 1 indicates the presence of trickle power required by the logic board to begin the
startup process. LED 1 should be yellow when the DIAG_ LED button is pressed, indicating that trickle voltage is present."

The yellow LED means the board receive good power from the PSU. Does the Mac chimes when the CPU is removed? The LEDs indicated theres no more problem with the Mac. What is the status of the front panel white LED? Does it stays on or does it flashes? If it flashes, how many times does it flash?

 

[Macstefws]

HackerWayne,

Thx for your kind reply!

Ad.1 Removed DVD drive => no diff
Ad.2 Cleaned and repasted, reseated CPU cooling towers, not a problem (no overheat LEDs light up either)
Ad.3 Both CPU are original X5150s, never changed

Trickle LED firm yellow light, Power LED firm green when pressing Diag SW
No chimes at all.
Front panel LED firm white light.

Powering on with only CPU A & memory raiser in slot A, GPU present LED flashes green during Diag mode.

Powering on with only CPU B & memory raiser in slot B, fail CPUB lights firm red, shortly FANs starts full throttle.

So assume I need to start focusing on 'GPU present' flash with only CPU A? Will also try to swap CPUs to try and figure out whether it's supporting circuits or CPU that's possible broken.

But still it should boot on only one CPU&memory board, right?

 

[Macstefws]

Will also try to swap CPUs to try and figure out whether it's supporting circuits or CPU that's possible broken.

Swapping CPUs it still the 'fail CPUB' LED that lights red, aka it must be on the motherboard supporting circuits that has an error.

Also with both CPUs swapped and mounted, powered on, thus still when pressing diag sw only firm green light in power led and firm yellow in trickle led, not light at all in GPU present or EFI led. Any known common causes on mother board affecting CPU B & GPU detection/usage, like worn out capacitors or other passive/active components easily acquired and changed?

 

[Macstefws]

Further analysis...

...shows that PSU, Memory Raisers and Video Card are all working in my other Mac Pro 1.1 aka assuming it most be something on the motherboard, only how to easiest/cheapest go figur out and fix it, clues anyone?

 

[666sheep]

Apple Service Manual states that faulty PCIe card may cause CPU LED to light.
I've seen several MR members with this issue and bad graphics card was always the culprit. Try boot your Mac without graphics card (or any other PCIe card, if you have any) with both CPUs and risers installed.

 

[Macstefws]

Apple Service Manual states that faulty PCIe card may cause CPU LED to light.
I've seen several MR members with this issue and bad graphics card was always the culprit. Try boot your Mac without graphics card (or any other PCIe card, if you have any) with both CPUs and risers installed.

Thx, only the Graphic card works fine in my other Mac Pro, so... but will give it a try, thou I just ordered a refurbished motherboard for it of eBay

 

[Macstefws]

Try boot your Mac without graphics card (or any other PCIe card, if you have any) with both CPUs and risers installed.

Nope, still turns on the fail CPU B LED woth out any PCIe cards plugged in

 

[Macstefws]

Problem solved... the expensive way

A refurbished/second hand motherboard solve the problem, I now have a second working MP 1.1.