CPU vs GPU

[jmrwd3]

Hello all! I am buying a new family iMac to replace our current model from 2009. Everyday use of the computer is limited to Microsoft Office programs and internet browsing, however I would like to use the machine to occasionally run XPlane 11. In trying to keep cost down, I have decided either to purchase an off the shelf 3.8 GHz machine which comes with a better graphics card (Radeon 580), or purchase the mid level 3.5 GHz machine and upgrade to the 4.2 i7 processor, however that would have the Radeon 575 graphics card.

Any ideas on which option might give me the best performance?
Thank You!!

 

[06tb06]

Even though both CPUs are rated 91-watt, for some reason the i7 chips will throttle more than the i5 chips. If most of your time is spent running productivity apps then you won't see much of a performance difference upgrading the CPU.

 

[jmrwd3]

Even though both CPUs are rated 91-watt, for some reason the i7 chips will throttle more than the i5 chips. If most of your time is spent running productivity apps then you won't see much of a performance difference upgrading the CPU.

That’s very helpful! That being said, do you feel the Radeon 580 is a worthy upgrade from the Radeon 575? Originally I was thinking of purchasing the mid-tier 3.5 GHz iMac.

 

[J.Gallardo]

http://barefeats.com/xplane11.html

Unfortunately, they don’t offer many different cpu measurements... But nice info for X-Plane users.
I’ve just ordered an iMac with 580 gpu, but stayed with i5. Hyperthreading in i7 would give you some more power, but I believe upgrading gpu is more system-wide noticeable.
Also check: http://barefeats.com/imaci5_v_i7_game.html

 

[Samuelsan2001]

That’s very helpful! That being said, do you feel the Radeon 580 is a worthy upgrade from the Radeon 575? Originally I was thinking of purchasing the mid-tier 3.5 GHz iMac.

X plane will love the better graphics, everyone else and every other use you have would far prefer a SSD instead of a fusion or standard HDD. I would skip both the upgrades and go for the 512gb ssd on the middle tier machine. Any further storage needs for files and media can just be added with externals.

If you decide you really d want a fusion drive make sure it’s the 2TB or 3TB option as they at least have 128gb ssd that gives pretty good speed most of the time, the 1TB fusion only has 32gb if ssd and is not a great choice.

 

[MacsRgr8]

I run X-Plane 10 and 11 a lot on my Mac.
I am lucky that I have the i7 and Radeon 580.

Point is both the CPU and GPU are really very heavily taxed, especially when flying with lots of extra scenery.... so yours is a tough decision.
However, the grfx settings I play at regularly exceed 4 GB of VRAM used.
Therefore, having the 8 GB VRAM of the 580 is probably more a necessity than the extra horsepower of the i7.

BTW... also get > 16 GB RAM (preferably 32 GB).

 

[J.Gallardo]

As you can see, probably 8Gb Vram of 580gpu would put i5 in pair with i7. (In chart, “boost off” means: disabled Turbo Boost in cpu).
I agree about SSD option, but gpu will be impossible to upgrade later. Fast external storage is getting better and cheaper every day. Reaching internal SSD speed is expensive, but totally possible: Sonnet offers a Thunderbolt external SSD (pci-e ssd) with comparable performance. It’s expensive: 1tb=1000$ (but not far from Apple’s internal price).
Getting Fusion Disk (the big ones: bigger ssd) & adding external usb3 ssd is not so expensive; it can fulfill your needs, and going faster will be more affordable in a near future.