HP Z800 with 2 x Xeon X5680 weirdness

[DGroves]

if HP thought the z800 would work reliably with a 500 watt supply it would have come with one, the fact that HP made the base supply 850 watts and the upgraded supply 1115 watts for a high end system is rather telling and you were quite lucky to get a 500 watt unit to work even though you had two low power cpu's

[EZGGWP]

Well, HP is a business. If someone buys the cheapest config of Z800, they would still pay a lot of money to HP for a replacement 850W PSU. They could make a lower power PSU, but that means more development and productions costs + less profits from low power units. 

[SDH]

From knowing DGroves' background and watching over the years I'd say his advice for the Z800 and Z820 workstations is the gold standard.  He's been using and enterprise-level maintaining these for quite some time now.  Experienced advice like that is hard to find...

Just checked on eBay and with free shipping used Z800 power supplies, 850W, are selling for 65.00 plus a bit of tax.  I've bought used eBay HP power supplies for years now to repair the rare failed originals.  I've never had one of those used eBay ones come bad or go bad later... over 10 years now. How much weirdness would you like to avoid?  You've had your share. I'd cough up the cash, personally.

I'm quite sure the missing cap/resistor is worth getting that processor replaced for.  I've been well served by honorable eBay sellers on bad processors bought used.  They generally believe you and honestly I don't think very many actually test each processor  they sell.  I'd contact the seller and give them a link to this post, and let them know you'd be happy to add good news to this post with credit to them for an honorable act.  I've had a few come bad from good eBay sellers and not one wanted me to send the bad one back. Given your care level I'm sure it came that way, especially since it has been an issue from day one.   Let us know...

Those X5680 processors had one sSpec code, SLBV5, and cheapest prices from good sellers on eBay is at $20.00, free shipping.  If there had been two sSpec codes it is ideal to always get the latest one, and to match the two you get.  This single code makes all that easy, but never get one starting with a Q... qualification sample, which is like beta version.

Good luck on your project ... you're close to the finish line!

[EZGGWP]

I appreciate DGroves' advice wholeheartedly, I'm thankful that he's replying quickly. As for replacement, I didn't buy it on eBay. In fact, I bought it here, in Russia. As you might know, there are difficulties with shipping stuff to Russia now. Anyway, that's not the problem now. I use ATX chassis and I don't think I have spare space to fit an original PSU, and even if I manage to find it (which I did not), it would cost much more than $65 in here. And even ignoring everything else, I kind of want that system to be janky. Initially, I spent like $180-200 on it, and it was very cheap for a 16 thread home server, so I want it to keep being cheap. With those X5680s it's now closer to $300, but it's still pretty cheap for a 24 thread 3.33GHz machine. Once again, thanks for all the help.

[DGroves]

while consumer systems are made to a price point workstations and servers are definitely not, HP produces these systems which are then usually bundled with specific addon hardware/software to perform a specific task and HP is not going to to Risk their reputation or get sued because of skimping on a part to save a few pennies

do as you wish, you asked and received a answer from two people who maintain/service systems in a business setting and both agree that a quality power supply in the range that HP used iswhat should be used as a replacement

[mals26]

Do you have a revision 3 motherboard?

[EZGGWP]

Yes, I have a "-003" board. The fact that it booted up with one CPU proves that my board supports these CPUs.

[mals26]

I had a 002 motherboard that would eventually boot (3 or 4 tries), but it would be unstable.

[EZGGWP]

Two things happened in past few day: I got my CPU back with freshly installed capacitor and I measured the power consumption of my system. Replacing the capacitor DID fix the memory issue, now CPUs boot with any amount of RAM installed. However, they only do so with one of them installed. Upon installing the second one, the system keeps rebooting. At that point I decided to measure the power consumption of the whole system by using a common multimeter in series with PSU plug. The max amperage I've seen was 1.36 amps @ 225 volts, which is around 300W. We discussed PSUs here a lot, but 300W is not even what my PSU should give on 12V rail only (which is 450W). There's still a chance that PSU gives much less than specified, and I'll still test that some day. 

[EZGGWP · Accepted solution]

Also, my fellow had a moment of witness and suggested that a used CPU might have microcracks in PCB that might become bigger under pressure of CPU cooler and lead to instability. I randomly tried to untighten one of the heatsinks and now the system boots up well. I don't even know for sure if that is the problem that was causing the faults directly, so this thread might not even be useful to anybody. Still, I consider this issue solved. Thanks again to everyone who participated.