Speed Difference between intel i7 and i5 under MacOS

As I've mentioned before, my old iMac was broken, but I managed to fix it.  In the intervening time, I bought one of the core retina iMacs instead.  Since this was an i5, I decided to benchmark it on some video transcoding that I do a lot of to see the difference between the machines in general.  e.g. # cores, speed, cache etc.  I also ran the comparison on my MacBook Pro as well. All machines have a native SSD and are running the latest build of High Sierra.

Machine information:

New:

• iMac Retina 5K 2-inch 2017
• Processor 3.5GHz Intel Core i5 (4 cores)

Old:

• iMac 27-inch Later 2009
• Processor 2.8GHz Intel Core i7 (8 cores)

Laptop:

• Macbook Pro 15-inch Late 2016 (Touch Bar)
• Processor 2.7GHz Intel Core i7 (8 Cores)

Details of test:

• Nightly build of HandBrakeCLI from 2018-02-10
• Uses all available cores if possible, as it's multi-threaded.  A good test of multiple cores.
• Mp4 file of 1920x1080 resized to 960x270 using Quality of 22.

Old	New	Laptop
14m 41s	10m 16s	13m 26s

Notes:

• New encoding details:

x264 [info]: using SAR=1/1

x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2

x264 [info]: profile Main, level 4.0

• Old encoding details:

x264 [info]: using SAR=1/1

x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2

x264 [info]: profile Main, level 4.0

• Laptop encoding details:

x264 [info]: using SAR=1/1

x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2

x264 [info]: profile Main, level 4.0

Conclusion:

1. The new iMac running at a higher clock speed but with fewer cores is definitely faster than the 9 year old.
2. The 9 year old iMac still does surprisingly well.
3. The laptop, even though clocked at around the same speed and with 8 cores, is still slower than the desktop.

Using a Mac as a second display

As previously noted (here), my old 8 core i7 iMac broke and was subsequently fixed.  In the intervening time, I had bough a new core i5 retina iMac, so the 2009 model is a little bit surplus.  What to do with it?

One option was to use it as a secondary display for the new Mac.  So I bought the correct Thunderbolt to Mini display-port adapter (link to follow), plugged it and suddenly I have 2 27inch displays.  The 2nd was a bit bright, but I discovered the keyboard on the old iMac still works, and I can change the brightness with the function keys.  Great, but that got me thinking.

If the keyboard is still working, what about the rest of the machines.  Articles on the web mention that you can still play music through the iMac while it is being used as a monitor, so what else is working?  As it turns out, everything.

I fired up screen sharing and connected to the old iMac and got the complete screen that I would have seen had the screen not been used in target display mode.  Everything works; Safari, Terminal, Photos, iTunes.  So, if I do need to connect to it and use some of that spare horsepower for video conversion, it's available and can be used.  Big tick for Apple, there.

Fixing a Borken(sic) iMac Display

My 2009 iMac decided to break down in the most unfortunate way just before Christmas.

I normally leave it on all the time, and when I came back to it, the screen looked strange with small yellow blotches all over the screen and was unresponsive.  Since nothing else worked I did the "hold the power down button for 10 seconds" thing to force turn off the machine and waited about a minute before restarting.

Bad news, the progress bar crept to about 70%, then the screen got corrupted again and the boot sequence failed.  This was annoying on more than one way in that I had recently upgraded the 1TB hard disk to a 1TB SSD for massively increased performance. (I would 100% tell anyone who wants to get more performance out of a machine to a) upgrade the RAM and b) upgrade to a non spinning-rust storage instance.  I digress).  So, this is what I was seeing:

I reset the PRAM and booted into safe mode.  This took a very long time, but I did manage to get a login screen and the desktop, but with VERY slow video performance,  and still had 5 yellow/blue stripes down the screen.  After logging in, I could reboot it back into normal mode, but it stuck at the Apple logo screen and failed to continue.

This is what it looked like in safe mode:

Redrawing the screen was painful, as you could almost see it working out what to do.  Video playback didn't work, but I was able to fire up Citrix and work from home for a while, but really, really slowly

.

I did some searching on the web and it looked like it was a video card issue.  Since it was well out of warranty, I phoned my local may authorised repair place and they agreed to take it and have a look.  Unfortunately they confirmed that it looked like a video card issue and there was very little to be done since these cards cannot be sources easily any more and are not manufactured.

So, I bit the bullet and ordered a new 2017 i5  iMac with 1TB SSD and waited for the pain to subside from the payment.

In the mean time, I did look further and found a reference to an iFixit post (see here ) which suggested dismantling the iMac and roasting the GPU in an oven for 10 minutes to rement and dry solder joints.

My hardware experience is very limited.  I added a 1 Mhz to 2 Mhz switch (yes, mega, not giga...) on my first Acorn Atom to boost the 6502 processor, but that really was the level of my hardware experience.

But nothing ventured..., so I bought all of the bits and bobs needed from Maplins (R.I.P.) and 3 weeks ago, after watching both of his video tutorials, decided to bite the bullet and give it a go.

Well, it wasn't easy, but the worst part was putting everything back together.  The ribbon cables on that machine are a real bugger to put back correctly.  I took both videos and went with a combination of removing as little as possible to get to the GPU and then followed the rest of the instructions, eventually baking the GPU card on 4 little foil pyramids.

Put it all back together and it worked.  Booted to High Sierra and all the graphics stuff works perfectly now.

What did I learn from this?

1. Broken GPU cards can be fixed by baking them in the oven.  It may fail later, but when you're at this stage, anything is worth a try.
2. Go slow and steady when trying some new hardware stuff.  I disassembled and re-assembled over 3 days giving me plenty of time to make sure I didn't rush anything.
3. Rare earth magnets are great at pulling screws from your hand, just as you try to screw the LCD panels back into a chassis... :-)