No, it won't cause the world to implode, or any problems for that matter. Make sure the 2x1GB and the 2x2GB are installed in corresponding banks to enable dual-channel memory mode. Yes you can, but personally, I wouldn't. Ram is so cheap now, you should just dump the 1GB sticks and get another 2x 2GB..
Also know, can I use different size RAM together?
“You Can't Mix RAM Size.” Generally, most laptops or computers come with two slots for RAM sticks, and sometimes more. For two different size RAM sticks to perform optimally together, they need to use the same voltage and their respective controllers should play well with each other and the motherboard.
Also Know, can you put 2gb and 4gb RAM together? As far as mixing size is concerned, the memory will work in what is called a "Flex Mode" - 2GB out of the 4GB and the present 2GB module which will run in Dual channel mode, while the remainder of the 4GB module (which is the other half of 4GB) will run in single channel mode.
Also know, will adding 1gb of RAM make a difference?
And yes, 1GB makes a big differences, especially when it is 25% of all the RAM. 1-2GB will not make a differences if u have 10GB or 12GB of the RAM.
Can I install 8gb RAM with 2gb RAM?
A motherboard with DDR2 slots will not fit any other types of RAM sticks. If your motherboard's memory capacity caps at anything above 8 Gigabytes, feel free to add an 8GB memory stick to your system. You can eventually replace the 2GB stick if your computer is still usable then.
Related Question Answers
Can I use 1333MHz and 1600mhz RAM together?
Hardware Brad : You can, both sticks will run at 1333MHz. As long as your motherboard supports more than 8gb of RAM, which most of them do.Can I use 1600mhz RAM on a 1333MHz board?
1600mhz RAM will work at 1600mhz, or any speed less than that. RAM speed is set by your motherboard and processor combination. In short, yes 1600mhz ram will work at 1333mhz just fine.Can you use all 4 RAM slots?
A common misconception about RAM is that you can put any RAM into any slot. You can do that, but it won't work, or it will work ineffectively. If you have four RAM slots, always buy matched pairs of RAM (two sticks from the same company, same speed, and same capacity) for the best results.Can I add 4gb and 8gb RAM together?
There are chips which are 4GB and 8GB, in dual channel mode this will not work. But you would still get 12GB total only a little slower. Sometimes you will have to swap the RAM slots since the detection has bugs. IE you can either use the 4GB RAM or the 8GB RAM but not both at the same time.How much RAM do I need for gaming?
8 GB is the minimum for any gaming PC. With 8 GB of RAM, your PC will be running most games without any problem, though some concessions in terms of graphics will probably be required when it comes to the newer, more demanding titles. 16 GB is the optimal amount of RAM for gaming today.Is 4 sticks of RAM better than 2?
General rule with Ryzen is always to prefer 2 sticks over 4. If you want 32GB get 2x16GB. 2x8GB will have better timings/speeds though. the more physical chips on the dimm, the denser the routing and the worse signal integrity you get.Is 32gb RAM overkill?
Is 32GB overkill? In general, yes. The only real reason an average user would need 32GB is for future proofing. As far as just simply gaming goes, 16GB is plenty, and really, you can get by just fine with 8GB.What is 1gb RAM?
1GB of RAM is 1024MB of RAM.Can I install 3gb RAM?
Yes you can install 3GB RAM on your PC but the first step to upgrading your RAM involves gathering a little information. First, you need to know how much RAM your computer has already. Under the General tab you'll see information about your computer and operating system, including how much RAM is installed.How much RAM can a processor support?
CPU Bit. If a computer is running a 32-bit processor, the maximum amount of RAM it can address is 4GB. Computers running 64-bit processors can hypothetically handle hundreds of terabytes of RAM.What can 1gb RAM do?
1GB of RAM is enough for basic operations like web browsing (don't expect to run a browser with dozens of tabs open though) and email, and some word processing and light image editing.Is 1gb of RAM good?
Unfortunately, 1GB RAM on a smartphone is not enough in 2018, especially on Android. The Android operating system can quite often use up to 1GB RAM or more on its own, which means the overall performance across every app and every interface will feel slow.Is 2gb RAM better than 1gb?
In your RAM scenario,more RAM translates to having more space to do stuff,because each program takes a bit of RAM,and web browsing with more than 3~5 tabs open can be quite a challenge,just having 1GB of RAM. But frankly,2GB is not that high of an improvement either.How do I identify my RAM type?
You can usually identify the type of RAM it is by the speed rating on the label, if it doesn't outright say the DDR type. If there is no label, you will have to google the model number printed on all of the chips.How do I know if dual channel RAM is working?
To find out if our RAM (Random-Access Memory) is running in dual channel mode, we now just have to look for the label called “Channels #”. If you can read “Dual” beside it, then everything is OK and your RAM is running in dual channel mode.Does RAM speed matter?
Faster RAM will give your PC better performance in certain specific benchmarks, but in terms of actual benefit to most users, having more RAM available is almost always better than having faster RAM. Graphics cards include their own memory, so games aren't majorly affected by system RAM speed.Is mixing RAM bad?
You are right about mixing different RAM modules—if there's one thing you absolutely can't mix, it's DDR with DDR2, or DDR2 with DDR3, and so on (they won't even fit in the same slots). RAM is pretty complicated, but there are a few things you can mix and a few things you shouldn't. In any case, I don't recommend it.How do I free up RAM?
Click Start, then type "Task Manager" in the search box. Click "View running processes with Task Manager" to load the Windows Task Manager. Alternatively, you can press "Ctrl-Shift-Esc" to bring up the Windows Task Manager. Click the "Processes" tab to see what programs are currently using RAM.What happens if you add more RAM?
Basically adding more RAM makes your computer able to have more applications opened at the same time and helps to keep most important and most used data in RAM so the access times will be faster. if an application needs 1Gb RAM to work and you have 4Gb it will not run faster if you add more RAM. 
