Fixing the Unfixable iMac Pro with Louis Rossmann!

[m8377]

For the question about having a bad ram stick, you can send back just the RAM sticks. If the stick failed it will qualify for the exchange pricing. Normal 8GB stick for a iMac is ~$200 CAD outright, and ~$100 exchange pricing. Not sure what the price to send back a dead ECC stick is. But if your mainboard is dead, you send back all your RAM, CPU, and MOBO. IMHO it's so that apple doesn't need to faff about with actually troubleshooting a difficult problem. Just swap out everything and be done with it. Even though every other computer can run very simple test to narrow down if it's CPU or RAM or MOBO specific issue with not too much effort. 

 

It's like ordering parts for a fancy microwave. If you break the plastic shield on the door, you have to order an entire new door. You could buy just the handle or just the hinge, but if it's any other problem you have to buy a different part that has hinge handle and your actual problem piece. 

[mariushm]

32 minutes ago, Unimportant said:

Happen to have part numbers for such a chip? I've never seen something like that before, and I fix a lot of SMPS from all kinds of fields.

 

Haven't seen a computer PSU using relays for ages now. I'd like to think a good PSU exploits the inertia provided by the APFC inductor to limit current peaks without resorting to clunky relays.

can't find one specifically for primary caps.. there are some for bleeding the X capacitors (for ac filtering, noise reduction) etc see below - it needs to bleed so user won't be zapped if cable is unplugged and user touches psu mains connector.

active pfc circuit will slowly drain capacitors in most psus even without bleeder resistors

 

latest psu review on techpowerup, no cherry picking: https://www.techpowerup.com/reviews/Cougar/GX-F750/4.html

 

 

Quote

The transient filter consists of four Y caps, two X caps, two CM chokes, an MOV, and an MPS HF81 that is described as an X capacitor bleeder by its manufacturer. The HF81's operation is simple: once placed in series with discharge or bleed resistors, it acts as a high-voltage switch. In the presence of AC voltage, the HF81 blocks current flow to the bleed resistors to minimize the power loss on these components. When disconnected from the AC voltage, the HF81 automatically discharges the X capacitor by closing the circuit through the bleed resistors and directing the energy away from the exposed AC plug.

 

NTC thermistor and relay to short it out of circuit:

 

[Unimportant]

9 minutes ago, mariushm said:

can't find one specifically for primary caps.. there are some for bleeding the X capacitors (for ac filtering, noise reduction) etc see below - it needs to bleed so user won't be zapped if cable is unplugged and user touches psu mains connector.

active pfc circuit will slowly drain capacitors in most psus even without bleeder resistors

 

latest psu review on techpowerup, no cherry picking: https://www.techpowerup.com/reviews/Cougar/GX-F750/4.html

 

Thanks, interesting stuff.

 

9 minutes ago, mariushm said:

NTC thermistor and relay to short it out of circuit:

Haven't seen that for ages. I wouldn't be happy with that solution tough.

 

[Brad Houser]

My guess as to why the memory and CPU were socketed, is that they had enough failures that were caused by bad memory or CPUs that they ended up throwing away good motherboards. Also having sockets for the memory allow different configurations without different motherboard SKUs, From an inventory management standpoint, the decision to build machines with different memory configurations can be done later in the manufacturing process. Another thought I had is that a significant number of memory sticks and CPUs were damaged in manufacturing, so adding them later reduces that failure rate. 

[Stefan Payne]

3 hours ago, Unimportant said:

Thanks, interesting stuff.

Haven't seen that for ages. I wouldn't be happy with that solution tough.

Yeah, much has changed in the last couple of years in terms of Power Supply Technology.

The good old Double Forward/PWM Topology is on its way out and is being replaced by LLC-Resonant Mode Topologys.

FSP tried Active Clamp (Reset) Topologys for a time but that's also on its way out.

There are some interesting things.

 

Sadly multiple independent voltage monitoring circuits that are monitored is also something you don't see very often these days (mostly only on be quiet and Bitfenix)...

 

17 hours ago, D13H4RD2L1V3 said:

Did he say the system has a 500W power supply?

For a Xeon and a Vega 56/64?

Yes, and?
If you have a quality PSU, don't overclock and use VEGA a bit under the Spec form AMD, there is no Problem with that. VEGA isn't as bad, its just pushed over the edge. With just 100 or 200MHz less Core Clock you'd see at least 50W less, maybe even 100W Primary.

[D13H4RD]

6 hours ago, Stefan Payne said:

If you have a quality PSU, don't overclock and use VEGA a bit under the Spec form AMD, there is no Problem with that. VEGA isn't as bad, its just pushed over the edge. With just 100 or 200MHz less Core Clock you'd see at least 50W less, maybe even 100W Primary.

Is it enough for an 18-core Xeon and a Vega 64 at full load though?

 

This is a legitimate question. Anandtech says the Xeon performs below TDP but I’m interested to know how much power the system consumes in total during a total sustained system load. An undervolted V64 should be significantly more efficient than stock but I’m not sure if you can tweak that on macOS.

[Eleven1111]

Why didn't Linus or Louis put the screen back on??

[Stefan Payne]

7 hours ago, D13H4RD2L1V3 said:

Is it enough for an 18-core Xeon and a Vega 64 at full load though?

 

This is a legitimate question. Anandtech says the Xeon performs below TDP but I’m interested to know how much power the system consumes in total during a total sustained system load. An undervolted V64 should be significantly more efficient than stock but I’m not sure if you can tweak that on macOS.

Yes, why shouldn't it?!

Sorry, I don't get why you are trying to claim that the 500W isn't enough, when it clearly is...

And the TDP Limit of the GPU is in the BIOS of the GPU!

 

Its not a problem at all...

[D13H4RD]

2 hours ago, Stefan Payne said:

Sorry, I don't get why you are trying to claim that the 500W isn't enough, when it clearly is...

Uh, what?

Quote

Did he say the system has a 500W power supply?

 

For a Xeon and a Vega 56/64?

Not sure where you got that from. That was a question and it could've been responded nicely with facts and links to sources. I even mentioned in the second post that it's a legitimate question.

[Beef Boss]

I don't understand how people weren't expecting Louis to make jokes about Apple, especially on a video and situation like this. I thought the jokes were funny, and well not as expected on linus's channel, just fine because of the situation. You cannot expect someone like Louis to not make a jab at Apple when they refused to fix a product they made. You guys think it's okay for a company to do this? 

[Atreides89]

It's quite baffling seeing how you guys experienced something that in my mind is so similar to what happened to me some years ago with the purchase of a 27" iMac. Granted I live in Guatemala City and had some suspicion with how technicians were trained here to service apple computers.

 

Maybe if you want to stick a while I can tell you a story of what my experience has been owning an apple computer, and although I think they have some really nice features, I'm also very aware of how their service doesn't reflect the high sticker price their computers have.

 

For me, the apple experience started in my university, where computer labs dedicated to architecture were built around the mac ecosystem of programs, and although I had never had any experience with the OS, I found myself really liking some of the ease of use, and during my third year of architectural schooling I decided to make the jump to that platform going for a top of the line 27" mid 2010 iMac with an i7 and 8gb of ddr3 ram (which I would upgrade myself to 16gb) with a 1tb hhd all for around Q26,000 (around 3,500 us$), during the first six months running my programs was one of the smoothest experiences I had had at that point and to say the least, I was impressed with my new system, although that was to be expected jumping from a dell XPS tower from 2006.

 

Problems started appearing after six months though, some occasional corrupted files and the computer randomly shutting down, freezes when ram utilization went over 12gb left me with no option than going to the apple certified store where I had bought my computer and there they charged a 500Q (around 66 us$) fee for checking and servicing the computer. After around one week of waiting I received an email stating my computer had been serviced and that they had found no problems but they had run a diagnostic tool to repair any errors the computer might have and that all should be fine now.

 

So back into the store I went pick up my machine and for some time everything seemed fine but problems reappeared again after a couple of months of usage and so I went back and after talking with the manager of that store and explaining what had happened instead of charging the usual 500Q fee they discounted it to 250Q (still around 33 us$), this time around though back home I decided to do some digging into what could be happening to my computer and found out my particular computer might be part of a bigger issue than I had anticipated with my model being eligible for a free hard drive replacement due to issues with seagate drives that shipped for that computer program.

 

I called the store and after talking with them they said that indeed my computer could be eligible for a hdd replacement but that I would need to wait for a couple of weeks for the part to arrive, and that I couldn't hold on to my machine until then because they needed the piece in place. So a new wait started and after a couple of weeks and not having any news I called them back and they said that indeed they would contact me in a couple of days more because the part hadn't arrived yet.

 

After multiple calls one month had elapsed since I had gone to the store to get my hard drive replaced and still no news until they called and said they finally had the part on their store so they could go ahead and swap the faulty part for the new one, finally after one month and some few days I would be able to have my computer back and hopefully it would work as intended!

 

I went to pick up my computer at the end of that week and I had one of the most unexpected surprises I've had with customer service, they were waiting with my computer already boxed and upon asking to inspect it there was a small chip on the bottom left corner of the glass screen cover (nothing I deemed to major to make a scandal, although it certainly irritated me since I had been so careful with this big investment), after they showed me my files had been transferred to the "new" drive I was ready to check out, but they were waiting with a bill for an estimated $100 for backing files up and changing the piece and there they stated that although the piece had been free, they still had to charge for the other work involved replacing the piece, and that's where things really started to go south for me in terms of expectations.

 

After getting back home and reinstalling my programs, I started noticing some weird interactions with the mail application (that I never really went around to configure) and there things got really weird, for one when I opened the app accidentally when copying a mail address and wanting to reply an email I noticed the app opened on someone else email account! COULD THIS really be happening!? 

 

Apple authorized store had replaced my hard drive for a used hard drive from someone else's computer and with that they had left me access to some of his accounts, a really disgraceful act which makes me really doubt how they treat personal information on their stores.

 

Also, they hadn't really replaced my hard drive for a new one!

 

After calling them and emailing them they refused to replace that hard drive stating they already had done so, but one more thing had happened that forced me to go to their store regardless of whatever was happening already; the screen was now showing after some minutes, sometimes hours of use a big vertical blue line on the screen.

 

So back I went to the store asking for a replacement of the screen 11months into the purchase of the computer so still within the boundaries of the apple warranty, and the store again started a long process of stalling, which ended up with them unable to place the order before the warranty expired and prompted a series of calls to the US offices to get them to acknowledge the error they had made, with so many things going on I also seeked help on the apple forums where "pro users" quickly stated it was my fault for not getting the extended warranty and to be honest made everything feel really bitter.

 

That was around the time after calling multiple times to the offices in the US I got to talk with a nice lady that was able to reverse the decision and extend the warranty for an extra one year, but after all this time I had taken my computer three times in less than one year for services and after taking it in for the third time in the 11th month, they had already had the computer on their end for 3 months now, after some more time waiting they said they had finally replaced the screen, and to be honest with all that drama I had in that period of time I quickly forgot about the hard drive..

 

After a couple of years more of regular use as a primary machine I started working more on a laptop as my main computer until this year where I started enjoying using some of the programs I had on my mac again, where after sitting without regular use for some time both the drive crapped out and the screen started showing signs of the blue line, this time though I bought a "iFix it" kit for opening up my machine and servicing my machine myself, had to buy some cables to enable me to read the temperature of my ssd and overall just make mac think it was a regular mac drive, but I guess what I really wanted to say is that their service really leaves A LOT to be desired, and that I'm glad you were somehow able to get your computer repaired.

 

I'm sorry this post took so long to read but I guess some experiences mark you, and I hope this story helps more people do a better purchasing decision in the future.

[Stefan Payne]

3 hours ago, D13H4RD2L1V3 said:

Uh, what?

Not sure where you got that from. That was a question and it could've been responded nicely with facts and links to sources. I even mentioned in the second post that it's a legitimate question.

Where is the Problem or what is your point?!
You were trying to claim thet both components consume way more power than they actually do.

 

And you can also limit the Power in the BIOS of the Components. Sadly there aren't any "VEGA 64 GREEN Edition" but there at least is something in that direction:

http://www.pcgameshardware.de/Radeon-RX-Vega-56-Grafikkarte-266624/News/Powercolor-RX-Vega-56-Nano-Edition-Computex-1256454/

 

ANd you also remember this thing?

https://www.techpowerup.com/reviews/AMD/R9_Nano/

[D13H4RD]

43 minutes ago, Stefan Payne said:

You were trying to claim thet both components consume way more power than they actually do.

??????????? 

 

I didn't and never did. I asked because 500W doesn't appear adequate at first glance. I later then found out through Anand that it's just fine. 

[lewdicrous]

On 7/30/2018 at 9:31 PM, Zodiark1593 said:

Petition for Linus to pay for Louis to go to Improv school?

Louis wasn't in his natural habitat