MacBook Pro 2018 13 inch vs 15 PCH vs. direct to CPU
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MacBook Pro 2018 13 inch vs 15 PCH vs. direct to CPU  


New Member
Joined: 2 years ago

Good afternoon,

I am looking into replacing my MacBook Pro mid-2015 15 inch with a new apple MacBook Pro. Aside from the heat throttling issues, which do make me hesitate a bit (and I am not even looking at the i9 processor), I was wondering how significant is the real life performance difference from the TB3 that goes through PCH vs. the direct to CPU path seen in the 15 inch MacBook Pro

I plan on purchasing a similar set-up to itsage (ASUS XG Station Pro + ASUS Strix GTX 1080 Ti). Looking at his recent build guides it seems like the 13 inch had 2719 memory read speed, 2266 memory write speed in Bootcamp on AIDA64 whereas the 15 inch had 2734 memory read speed and 2247 memory write speed on AIDA64.

On the external monitor Unigine valley score was 4672 vs. 4974 (13 inch vs. 15 inch). Unigine heaven score was 2877 vs. 2865 (13 vs. 15 inch). 

I am a technical novice so I admit it is possible I am looking at the wrong details on this. But do you all feel like the PCH is enough of an issue to go 15 inch if possible? 

Thank you for your thoughts and help on this,

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts

Famed Member Moderator
Joined: 3 years ago

@taelvin I'm no expert but PCH won't matter much. Base your decision on other factors more important to you. I went for the 15" because I wanted higher CPU performance. Otherwise just for eGPU use 13" is a no-brainer and money-saver (relatively ;p) for a student like me.

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2018 MacBook Pro 15" RP560X + RX 5700 XT (Mantiz Venus)

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2018 15-inch MacBook Pro

itsage liked
Illustrious Member Admin
Joined: 3 years ago

@taelvin The 15" MacBook Pro has the performance advantage due to direct Thunderbolt 3 to CPU connection but real life difference is not significant. If you like the small footprint of the 13" model, I'd say go for it instead of the 15".

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