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mac pro does not power on

H

horvazs

macrumors newbie
Original poster
Apr 10, 2009
20
0
Budapest
Hi,
I would need a little help here.
One day I had a weird idea to build mac pro from parts. No problem so far, slowly purchased everything needed, logic board, processors, memory, video card, case, psu, cables etc... so it is really a long story.So far I was not brave enough to add all cost together, probably could have bought a retail one, brand new for sure.
Anyway which makes me sad now that after I put everything together it just doesn't start up. Does not give any signal. The only thing is when I press the diag_led button the 1st led (yellow) is on "standby" which means the trickle power is sufficient. But even if I press the power on button nothing happens, no more led lights on. (PSU I tested out of the case, at least in all connectors the 12 V is there)
Any suggestion how I should test whether there is anything wrong with the PSU or the front panel board?
your comments are appreciated
thank you!
Zsolt

- Mac Pro Logic/Mother Board 2.8/3GHz 661-4449
- 2 pcs Intel Xeon E5462 2.8 GHz processors, L2 12 MB
- Nvidia 8800GT
- 4x 4GB=16GB DDR2 800Mhz RAM MacPro FBDIMM
- mac pro 980W PSU 614-0383
 
Do you have all the fans?

There are detectors that make sure the fans are there and running to prevent overheating, so if the full set of fans aren't there, it won't power up.

There could be other sensors that might be needed as well.
 
thanks for your reply
no, actually the processor heatsinks + fans are not installed yet. Can it really be that causes the issue and even the power led on the logic board is not on?
Is there a way to simulate the fans, the apple original ones still on the way, just wanted to make a test. What is still missing is the hdd ambient sensor, but honestly speaking wouldn't have expected that without it the mac won't start.
 
EDIT: I started writing this before there were any other replies but:

--
This is a very compelling story. Unfortunately there's not enough specific information for anyone to offer you a meaningful direction out of the hole you're in.

I think it's cool what you did and I bet you didn't pay more than the 20% extra a loan company would have charged. So essentially you bought you're Mac Pro on time. Had it powered up you'd look a bit of the genius. :)

Did you take all the safety persuasions like working on a metal or tin-foil covered table-top, wearing a wrist-ground on both hands, trying not to touch anything that could zap anything (card edges, solder points, etc.). Did everything arrive in sealed anti-static bags with no bag or box damage? Are you checking all the obvious details like shunt blocks (jumper settings), clock and pram batteries, cable types and configs, etc.? Did you reseat all the connected components? Did you check that there's no thermal paste on the CPU pins/pads? Did you turn it on before you set the heat-syncs in place (which would be bad!)? Is 800 the right memory? Are the memory trays the right version for that MB? Does E5462 work in that MB? You know that only testing voltage doesn't actually ensure that the PSU is good right?

Maybe set it up and start doing things that will help you isolate components. Try it with just one CPU, then the other, rotate the RAM, try an alternate video card if you have one, etc.

I dunno. There's too many things that it could be and not enough information to go on.
 
cmaier said:
Not even heatsinks? I wouldn't power that thing on without thermal sensors, heatsinks, and fans.
Click to expand...

Indeed... I dunno about xeons but with consumer class CPUs you've got about 20 sec. before they fry with no heat-sync.

That said, he might be saved by what iVoid said. Better prey he's right!
 
thanks for all comments. certainly
I don't want to run the mac without heatsink and fans, just a simple test for a second whether all what I put together sofar is working. According to the seller (PC-PartsExpress) of the logic board the E5462 xeon should work with it. Of course I cannot test each and every part separately but I think how I put everything together is pretty ok. I am having macs for years, apparently a G5 and have built couple of pcs (however I know that is a different story :)
Hope what iVoid said causes the issue and after the fans have been installed the mac would finally work.
 
will it even power on without heatsinks and fans? I'd think there'd be some kind of protection on the board because those processors can get very hot very fast without any kind of cooling.
 
I was curious and disconnected the sensors and couple of fan plugs in my G5 to see what happens. Nicely started up. May the concept is somewhat different from mac pros but...
Anything special I should have set on the logic board, EFI, firmware upgrade whatever?
 
Tesselator said:
Is 800 the right memory? Are the memory trays the right version for that MB? Does E5462 work in that MB? You know that only testing voltage doesn't actually ensure that the PSU is good right?
Click to expand...

Speaking about memory... has the OP installed the ram in the correct order?
 
not yet, I need to wait till Tuesday when most probably will have the heatsinks. I wish I could have them today, not easy to do nothing just waiting not knowing whether it will be any better with my mac pro then...
 
no problem, however would not look much differently than a normal mac as every part is original. Anyway will post it here soon (tomorrow)
 
probably you are right but than the case and PSU fans would not function properly as they do in a closed case.
Anyway only few screws thats all. Will send some pics soon just my camera is in my other flat, will take it tomorrow evening.
 
this is not for savings just for fun. My actual G5 is getting slow nowadays...

I haven't made the calculations yet but let's see. There were parts I bought in different currencies USD, GBP, EUR therefore the USD sums are just approx.
(all sum now in USD)
- logic board, 584
- 2 processors, 940 (2 x 2,8 GHz, 2 x 4 core)
- 16 Gb RAM, 600
- video card, 160
- case + PSU, 430
- memory risers, 60
- heatsinks, 300
- sas hdd + control, 360
- other accessories, 400

Sum: 3834 USD if I calculated correctly, with some add costs I am at 4000 then.
But the adventure to put everything together is priceless :)
(a little thing is that the mac still does not run)

Haven't checked how much a new mac pro with similar specs would cost.
 
horvazs said:
this is not for savings just for fun. My actual G5 is getting slow nowadays...

I haven't made the calculations yet but let's see. There were parts I bought in different currencies USD, GBP, EUR therefore the USD sums are just approx.
(all sum now in USD)
- logic board, 584
- 2 processors, 940 (2 x 2,8 GHz, 2 x 4 core)
- 16 Gb RAM, 600
- video card, 160
- case + PSU, 430
- memory risers, 60
- heatsinks, 300
- sas hdd + control, 360
- other accessories, 400

Sum: 3834 USD if I calculated correctly, with some add costs I am at 4000 then.
But the adventure to put everything together is priceless :)
(a little thing is that the mac still does not run)

Haven't checked how much a new mac pro with similar specs would cost.
Click to expand...

Completely!! Especially when you eventually have all the part and the thing still won't power up... Headache?
 
Honestly it could be any number of things. But start with removing as many variables as you can.

Did you test the PSU with a volt meter?

How about the leads on the front connector?

Take it out of the case. It could be grounding to the case.

Assemble it on a non-conductive table. Remove all the ram from it. Keep one stick in the first slot.

Make sure everything is very firmly seated.

The computer WILL (or should in your case) power on without any fans or sinks connected.

Make sure all the power leads from the PSU are hooked up correctly, as there are a couple of them.

I have done a couple tear downs on the various mac pro models, and they are complicated machines to the uninitiated.

Let me know how the above steps work out, and maybe I can offer more advice.

Jon
 
Hi, Jons
thanks for your reply.
- PSU I tested out of the case. Shortcut 7-9 pin in C connector can hear that PSU switches on and can measure 5 and 12 V in all connectors.
This is eg. what I don't hear when everything is connected to the logic board. What is the moment PSU should switch on?
- front connector cables seem to be ok but nothing happens if I press the start button, not even the led lights on. (tested it separately, ok)
- took out the logic board, cleaned again the ram and riser connectors with PVA cleaner, same with the video card.
But same symptom, no green led only 1 yellow if I press the diag.

Is there any way to exclude the front panel somehow to test whether there is wrong sg?
thanks
Zsolt
 
- nothing else connected
no fans, no harddisk or dvd.
Tried to use only one cpu, switched them in all possible ways, no luck.
 

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Have you tried with both RAM riser boards inserted?
I'm not certain but I think having one missing may stop the computer from starting up.
 
yes, have tried with both risers installed not any better unfortunately...
neither if memory modules have been changed in various ways.
I think the main issue is that for some reason the PSU doesn't switch to power mode. I don't know whether the logic board or the front panel controls that function.
Should the logic board be powered from the moment the AC plugged or when I press the power button on the front panel?
Still my question whether there is a way to exclude the front panel from the circle?
 
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