MacBook Pro 13” 2015 running extremely slow

[Domwood]

Hi, I recently bought two MacBook Pro’s, one with a broken screen and one with no power.

I tested the one with the broken screen on an external display and found no issues.

now I have transferred the logic board into the MacBook with no power it is running incredibly slow, it takes minutes to boot and minutes to load safari. I have ran it with the battery unplugged, this made no difference. I have also tried two different SSDs with no difference so I’m sure it’s not a software issue. I have all the parts from the other laptop still. I’ve also reset SMC and VRAM. I’m struggling to install any software to do any tests.

the fan also appears not to run, however in a hardware test it runs

It was running slow in the internet recovery mode aswell.

I recently transferred the logic board bsck too the other MacBook and it still ran very slow.
CPU idle is between 5-10% when doing nothing. 70 system 20 user

Any help would be much appreciated

 

[Analias]

The fan does not spin on these models till it detects sufficient heat. You have a sensor issue somewhere that is causing throttling. Commonly it's the battery or trackpad that causes the issue, but unfortunately you can't just unplug things as cutting the communication channel to the logic board throws a different error with the same outcome. As the issue persists when you place it back in the original Mac, it is likely that you have damaged one of the i2c communication channels while transferring the board. Inspect it carefully for any missing components. To figure which sensor is the offender on pre 2015 models I use ASD. Apple didn't produce ASD for the 2015 and onward models.

 

[Domwood]

The fan does not spin on these models till it detects sufficient heat. You have a sensor issue somewhere that is causing throttling. Commonly it's the battery or trackpad that causes the issue, but unfortunately you can't just unplug things as cutting the communication channel to the logic board throws a different error with the same outcome. As the issue persists when you place it back in the original Mac, it is likely that you have damaged one of the i2c communication channels while transferring the board. Inspect it carefully for any missing components. To figure which sensor is the offender on pre 2015 models I use ASD. Apple didn't produce ASD for the 2015 and onward models.

hi, thanks for the reply. Is this a fixable issue?

 

[Analias]

Of course it's fixable, it's tracking down the problem that's the hard part.

 

[glintoz]

I had a problem with my MBP 2015 overheating and freezing - replaced the thermal paste and it is a different machine.

I never used to hear the fan, now with the new thermal paste it is running hard when it hits high load. I would suggest doing the thermal paste as a start and see if that changes how the fans behave. It is a cheap fix although it meant I didn’t end up buying the a new machine.

 

[Domwood]

Of course it's fixable, it's tracking down the problem that's the hard part.

Sorry, I meant if this is a simple job or a job that will require a lot of skill and knowledge
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I had a problem with my MBP 2015 overheating and freezing - replaced the thermal paste and it is a different machine.

I never used to hear the fan, now with the new thermal paste it is running hard when it hits high load. I would suggest doing the thermal paste as a start and see if that changes how the fans behave. It is a cheap fix although it meant I didn’t end up buying the a new machine.

I was thinking about that, but the laptop never runs good, it’s slow from the startup so I doubt it’s a thermal issue

 

[Analias]

Like I said, the hard part is diagnosis. ASD (Apple service diagnostics) would make diagnosis a breeze, but without it it can be arduous. From what you've said, with two of everything it should be pretty easy to narrow the problem to the board itself, and as it was working fine before, you'd have to suspect you damaged the board in some way. From all that evidence, you'd have to suspect the damage would most likely be physical and you should be able to spot it with your eye. As far as fixing it, you'd likely require a hot air soldering station and of course the skill to use it.

Head on over to https://boards.rossmanngroup.com
And post your question there. There are some extremely knowledgeable people there that might have an insight.