iMac M3 slowing down...

[mikelamar]

I've iMac M3 chip, Ram 24 GB, late 2023 running Sonoma 14.7.2 and a week ago I added a DELL Monitor P2423DE 23,8'' 2560x1440 IPS, USB-C, as an extension.

Sadly I realized that my iMac slows down and lagging and many times flashing.
I don't know why is this happening or if it can be fixed but I'm very very disappointed.
I'd appreciate any help.

 

[Fishrrman]

If you UNPLUG the Dell display, do the "speed problems" go away?

Unplug it and run it for 2 days that way, to be sure.

 

[casperes1996]

OP, could you elaborate on the “many times flashing” part?
Try running an Apple Hardware Test. Power off, hold the power button until you get a list of startup options then hit cmd+D.
Try seeing if the issue occurs with a guest account on the Mac. If so it’s a software setup issue on your main account.

 

[mikelamar]

When I turn off the other monitor, everything run smoothly

 

[mikelamar]

OP, could you elaborate on the “many times flashing” part?
Try running an Apple Hardware Test. Power off, hold the power button until you get a list of startup options then hit cmd+D.
Try seeing if the issue occurs with a guest account on the Mac. If so it’s a software setup issue on your main account.

There's not a hardware problem. The monitor flashing stopped when I updated to 14.7.2 (it was only flashing when running InDesign and the second screen was on).
I will try the guest account and a cousin is bringing new cables and a thunderbolt hub to make some tests.
I'll keep you up to date.

 

[mikelamar]

There's a big disappointment in my face the last few days. Tested new thunderbolt cables, thunderbolt hub, hdmi...still lagging. Even when only running Backgammon Masters with the second monitor on I have a lag.
I also tested Indesign, photoshop, msword, acrobat and firefox with 3-4 tabs open. I've 7GBs free ram and the mouse is lags and sometimes jumps.

Just turning off the second screen and everything runs smoothly.

 

[casperes1996]

There's a big disappointment in my face the last few days. Tested new thunderbolt cables, thunderbolt hub, hdmi...still lagging. Even when only running Backgammon Masters with the second monitor on I have a lag.
I also tested Indesign, photoshop, msword, acrobat and firefox with 3-4 tabs open. I've 7GBs free ram and the mouse is lags and sometimes jumps.

Just turning off the second screen and everything runs smoothly.

Does it lag on both monitors or just the Dell? Did you try with the guest account?

 

[mikelamar]

Does it lag on both monitors or just the Dell? Did you try with the guest account?

It's only lagging on iMac...

Does it lag on both monitors or just the Dell? Did you try with the guest account?

Yes I've tried to guest account...same ****...