Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I followed the link you gave me but there is no more information about upgrading memory on my Mac 21.5-inch, 2017 than this:

3. Memory is not removable by users on iMac (21.5-inch, Late 2012), iMac (21.5-inch, Late 2013), iMac (21.5-inch, Mid 2014), iMac (21.5-inch, 2017), iMac (Retina 4K, 21.5-inch, 2017), and iMac (Retina 4K, 21.5-inch, 2019). If the memory in one of these computers needs repair service, contact an Apple Retail Store or Apple Authorized Service Provider. If you’d like to upgrade the memory in one of these models, an Apple Authorized Service Provider can help. Before you schedule an appointment, confirm that the specific Apple Authorized Service Provider offers memory upgrade services.

I have 8 Gb of RAM but I actually don't think that RAM is a problem, but rather a graphic card. I think that because my old Mac had 8Gb of RAM and it was fine with any tasks in Photoshop and Illustrator.

Can someone please tell me if the graphic card on this Mac can be upgraded?
 
2.3 GHz Intel Core i5
8 GB 2133 MHz DDR4
Intel Iris plus Graphics 640 1536 mB
2017 21.5" iMac with dual core processor. This really is a very low end Mac.
I wanted to ask your opinion about this computer because when I started doing something in Illustrator on it yesterday Clean myMac alerted about heavy memory usage even though I haven't really done anything complicated in Illustrator by then.

I know 16Gb of RAM is surely better but there weren't refurbished Macs with 16Gb of Ram on eBay. I had to buy on eBay because the applications that I want to use won't work on M1 chip so buying a refurbished Mac from apple was out of the question. On top of that I never had more than 8Gb of RAM on my old Mac and I didn't have any problems really.

Would you say that the iMac I bought is not fit for computer graphics jobs?
I would say not fit (others may disagree) for anything except light graphics work. Counting against you is 1) only dual core processor, 2) only 8 GB RAM, 3) you don't say, but low end models are either hard disk or fusion drive, 4) basic graphics.
If yes, is it possible to upgrade a graphic card at least? I heard that RAM cannot be upgraded on Macs made in 2017.
No. The graphics is not a graphics card, it is part of the Intel chip. The RAM restriction only applies to 21.5" model - 27" can be upgraded easily.
Could you give me your advice? I still can return this Mac if I have to.
Really depends on your budget. I would return it, but can you afford something better? By better, I mean: at least 4 core CPU, 16 GB RAM, internal SSD.

One way forward if budget is issue and your system is hard disk model (not fusion or SSD). You would gain performance by getting an external SSD as your macOS boot and working disk.
 
  • Like
Reactions: MagicMolecule
Please let me know which software you have that requires an Intel Mac. Also the version of macOS you’re using. I’m not aware of any software that runs on modern macOS versions that will not run on Apple Silicon. Either you’ll teach me something I wasn’t aware of or perhaps I can help you get things operational.

FYI: Your choice of iMac is incredibly weak. I understand that paying more money isn’t an option for everybody but if it is, and you do indeed need an Intel Mac, there are many better options than what you chose.
 
One way forward if budget is issue and your system is hard disk model (not fusion or SSD). You would gain performance by getting an external SSD as your macOS boot and working disk.
Thank you for the input.

There is a 2017 iMac for sale on eBay right now by auction with ends tomorrow, I could buy it.

Apple iMac 27" 5k (2017) - 4.2GHz Quad Core i7, 16GB, Radeon Pro 8GB & 500GB SSD

Could you possibly tell me what would be the maximum reasonable price to pay for it?
 
Thank you for the input.

There is a 2017 iMac for sale on eBay right now by auction with ends tomorrow, I could buy it.

Apple iMac 27" 5k (2017) - 4.2GHz Quad Core i7, 16GB, Radeon Pro 8GB & 500GB SSD

Could you possibly tell me what would be the maximum reasonable price to pay for it?
https://www.mac2sell.net/ used to be a reasonable reference. There are plenty others, I just haven’t used them. Input the info you have and see what price it spits out.
 
  • Like
Reactions: MagicMolecule
Please let me know which software you have that requires an Intel Mac. Also the version of macOS you’re using. I’m not aware of any software that runs on modern macOS versions that will not run on Apple Silicon. Either you’ll teach me something I wasn’t aware of or perhaps I can help you get things operational.

FYI: Your choice of iMac is incredibly weak. I understand that paying more money isn’t an option for everybody but if it is, and you do indeed need an Intel Mac, there are many better options than what you chose.
Hi.
Software Adobe CS5. Right now I have High Siera.

Are you calling Apple Silicon the last generation M1 Macs?
 
https://www.mac2sell.net/ used to be a reasonable reference. There are plenty others, I just haven’t used them. Input the info you have and see what price it spits out.
thank you so much I found out now what the price should be.
Could you possibly tell me if there are 21.5" Macs out there with specifications similar to these ones?
Or only 27" Macs were made with such good specifications?
 
Hi.
Software Adobe CS5. Right now I have High Siera.

Are you calling Apple Silicon the last generation M1 Macs?
ah yes. That will not work on a modern macOS as it's 32-bit software.

Apple Silicon on the Mac is all hardware running an M1 or better (for now that's M1, M1Pro, M1Max, M1Ultra, M2, M2Pro, M2Max)

Thus if you need to run Adobe CS5 you will need an Intel Mac running macOS (Mojave; 10.14) or older.
 
  • Like
Reactions: MagicMolecule
thank you so much I found out now what the price should be.
Could you possibly tell me if there are 21.5" Macs out there with specifications similar to these ones?
Or only 27" Macs were made with such good specifications?
The 27" model offered superior CPUs, superior (dedicated/discrete) GPUs, and user replaceable RAM compared to the 21.5" iMacs
 
  • Like
Reactions: MagicMolecule
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.