How to increase my vram

Which 2013 model iMac do you have? There were three (two 21.5 and one 27-inch) build models

with a few variant builds in each of them. Plus a few custom built to order models.

•How to identify iMac models - Apple Support

Generally, you cannot upgrade the VRAM in most desktop computers, with exception of Mac Pro

(tower) prior to 2013, or earlier PowerMac (tower) that allows one to add or remove graphic cards

and other components on the logic board. And cannot upgrade, standard RAM, going forward in

most Macs, with exception of the Mac Pro (tower) and the 27-inch iMac models.

Some models share standard RAM to boost the graphics capability, so it's wise to get the iMac or

MacBook with enough standard RAM so that is shared without slowing other system function.

Depending on the model build of product in question, specifications will vary. So a need to identify it.

You can check with the everymac.com database online to see specifications of most Macs ever made.

Also you can look into the download database application from http://MacTracker.ca to see most builds

of Mac product and several other Apple products, to include the specification and upgrade possibilities.

Where that still may be possible, sites such as OWC macsales may offer upgrade or replacement parts.

With integrated graphics, the only way to upgrade or add performance to the GPU is to be sure there

is adequate standard RAM, since that is shared. With dedicated graphics, these usually have their own

VRAM affixed to the graphic processor card, and it is not upgradable. Except in some tower models.

Or in a few rare cases, when a hobbyist takes apart a computer & solders other parts inside not intended

by the manufacturer, usually after the computer has failed and no longer under any warranty...

In any event...

Good luck & happy computing! 🙂

There is no way to do this in an iMac.

The GPU is a dedicated GPU that is not upgradeable.

Plus, if your 2013 is the 21 inch screen model, the new slimline 21 inch screen iMacs are glued up/sealed up computer appliances, now.

There is nothing upgradable in these iMacs until the AppleCare warranty expires, where, If you so desire, your only upgrade option is to upgrade the RAM from 8 to 16 GBs. You need to unseal and reseal the iMac's case to perform this RAM upgrade.

While the GPU in the 21 inch screen iMac models is a dedicated one, the GPU chip is directly soldered to the iMac's main logic board and is not a removable/interchangeable component.

No iMac has any interchangeable components other than RAM modules and, perhaps, the iMac's main internal hard drive.