HP Z600 NO BOOT

[BLACKBOXKING]

Hello

i have an HP Z600 WORKSTATION ( fm048ut#a ) i got from an auction over a year ago.

A few days ago i went to turn it on and it does not want to boot.

It will power on, the led light on the power button is always Blue, harddrive light only comes on when i force computer off but it does NOT make it to Post.(i have notice that when i turn it on it will sometimes turn itself back off within a few seconds(the longest just under 10seconds))

Fans are on & very loud, sometimes seems to run even faster after a few seconds of running. There are no beeps or any flashing light.

I have ruled out the 3GB of Ram, the Nvida Video card and other devices. i have done a bios reset/clear cmos. nothing has changed
I believe the CPU is working great. If i remove the cpu and power on the computer it will beep and flash RedLeds.

The Motherboard looks fine & i believe works well, but cant completely rule it out, because i dont have tools to check.

Cant completely rule out the power supply, i dont have any tools to test it but based on the green light on the back it is working well. 

I have read that it might be a Temp Sensor...Can someone tell me if this is the likely cause and if there is a way for me to remove or see the sensor & possibly fix/replace?

[SDH]

I don't have a Z600 to dink with, but the thermisitor that , if bad, causes very high fan speeds in other earlier HP workstations is included in the front power cable assembly.

Can't be sure if that is the case here, but search on eBay and look for that type of cable assembly for the Z600.

In every case I have been involved with that deals with way too high fan rpms it is either that the fan has lost its HP PWM throttle, or the thermisitor is reading too high or too low.

Keep us posted on the solution......  added are two pics of the front power switch cable assembly for the Z600 that usually has included the thermisitor, but I can't see it in there.  It might be now a part of that PCB.... the idea is to measure the ambient air temperature and have the motherboard adjust fan RPMs off of that.  Thus, the thermisitor has always been out front, rather than back in the case.

[BLACKBOXKING]

I was able power it on without this cord plugged in.
So far it still does the same thing. Fans running on high.

Powers up but still doesnt show anything on the screen, not even post.

so for now im ruling out the powerbutton/temp sensor.

have any other suggestions? im hopeing that it isnt the motherboard cause that would suck(around $250 to replace)

[SDH]

From all the prior posts related to having a thermisitor that has gone bad and caused the fans to run way too fast the pattern is this:

If the thermisitor sees the ambient air temp as incorrectly too high or too low the fans go fast.  So if the motherboard's firmware sees no ambient air temp at all (by you unplugging the cable set fully) it seems logical that the response would be the same.... run the fans very fast to protect all the hardware from overheating.

I'd do what I suggested first.... get a replacement and try that out.  If you have a known good Z600 I'd borrow the cable assembly from that to test with first, and then if it fixes the problem you can buy new from HP, or possibly used from eBay.  These things don't go bad often.

Keep us posted on what ends up working, if you can.  Here is an image I just captured off the HP PartSurfer system, and the HP info there proves the thermisitor is embedded in the cable:

[Dan_WGBU]

BLACKBOXKING, a missing or broken thermal sensor will not prevent the system from booting.  It can cause the fans to ramp at full speed, as others noticed, but the system will boot. 

The symptoms sound like a defective motherboard.  If the system does not start to POST, that is, it cannot even read the onboard system BIOS, the fans will start to ramp up to full speed and be very loud. 

It is hard to diagnose a bad motherboard.  You already swapped most items.  A corrupted BIOS image could cause these symptoms.  Try putting a jumper on E15 (2-pin jumper near the large 18-pin P1 power connector) then powering up the system.  Something should show on the screen.  If you don't have a jumper, the green on on E49 (by the Slot4 latch) can be "borrowed", if you don't mind clearing a BIOS password (if you use one).  

Putting a jumper on E15 actives the ROM recovery process.  There should be a desription on how to do this on the web, using a BIOS image on a USB flash drive, but I have not tried this process in many years.  FYI.

[BLACKBOXKING]

hey dan. do you think you can upload a small picture of the jumper on e15? i wish to make sure i have the right one.
So far it does the same thing, nothing on ether screens i use, and nothing appears to be loading.

Right now it seems like it is the motherboard(unless you have something else for me to checkout).
i will have to see if i can replace it some othertime. (ahhhh that sucks...)

[SDH]

This image, taken from the Z600 service manual (first edition) may help you.  The two jumpers Dan refers to are hard to see in the image, but they are pointed to by numbers 14 and 11.  Number 13 is the large main power connector he refers to.  E15 and E49 will be printed on the circuit board very close to those jumpers, respectively, but in a very tiny font.

Here's a picture in same orientation:

[BLACKBOXKING]

Still nothing...

i was going to see if i could turn it into a good gaming computer but  now im just going to try & replace the board sometime this summer. 
i wondering if i should skip  z600 and go for z800 desktop to use as a gaming desktop.
also do you all have some recomemendtions on parts.
Some that can handle crysis 2 , the Witcher 2, Just cause2 & space engineers on goodsettings but Not spend a ton.

thanks

[BLACKBOXKING]

I have a different board getting the same problem, unless its defective too, i have to rule out the board and move on to power supply or cpu... anyone have any suggestions/ideas?

[DMilford]

Hello all,

It looks like you have been getting some good help on here. If the fast fan issue is not resolved by the front power button/thermal sensor cable assembly, then it is usually caused by a failed systemboard. Certainly, try a BIOS boot block recovery and/or CMOS reset as these are quick and free. Power supply is certainly worth trying, but if you have to purchase one and that does not resolve the issue then it could seem to be a waste of money.

As for the "should I skip over the Z600" question, I would say yes and get a Z620 or Z420 and not a Z800. The Z600 and Z800 are now 3 generations back, not 2, since there were actually two different revisions of the Zx20 series. The Z420 comes standard with a 600W power supply which should be enough to handle most modern gaming graphics cards. If it is for gaming, I would recommend purchasing a new video card rather than trying to find a system with a powerful old card, as performance progresses quickly with those, and that will get you the most performance for the money. Most good PCIE video cards should work in one of those systems, as long as it is not TOO powerful (>150W).