I want a computer with really big RAM. 15 GB is not enough for me. First thing I know that I have to install Windows 7 Professional instead of Home Premium. However, what about the computer itself? I went to a computer shop and I didn't find a computer with more than 16GB of RAM. Where can I find that? or do I need to build that myself?
You need to have a 64bit machine, and a motherboard which accepts more than 16GB RAM
It may be a custom build, it may be not.
When looking at computers, read up what the motherboard is and what it can offer. If a motherboard states it can accept 24GB and has 6 dim slots, then you can install, for example 6 * 4GB RAM chips.
For example, and honestly choosing this board at random, the following https://www.asus.com/Motherboards/P9X79/ supports up to 64GB RAM
Most consumer shops only offer computer configurations with the most used options. However often those computer support more RAM than in the offered configuration.
Without going into too much detail:
- Look how many memory modules the motherboard supports. (For consumers motherboards this is often 4, but sometimes 6 or only 2)
- Look which side memory modules are supported.
- Multiply those.
Most of the times you now have your answer.
Next check this in the motherboards manual, because there are a few boards out there which do not support using the maximum sized DIMMs in all slots. E.g. due to chipset restrictions.
Quick and dirty trick to speed this up rather than reading a lot of manuals:
1) You can also find the information on sites such as Crucials memory configurator or Kingstons, or any of their competitors.
2) You can often just look at the motherboard.
E.g. the desktop I am typing this on is a 6 year old build on a Gigabyte UD5 motherboard with 6 memory slots. These are easy to recognize in the picture.
[Edit] Dave's comment on per process memory usage being limited is correct if you still use ancient 32 bit applications. However these days any OS can use 64 bit (I am ignoring the 10 year old thing called XP) and almost any application can be recompiled to use 64 bits address space. The only problem is if you use old pre-compiled applications. Sadly this is still the case on windows, but things are steadily improving there.