Reposting from another thread where I answered the same question.
I did face severe technical issues during my last GMAT (Online) attempt, which might have lowered my score by 10-20 points. I have seen a couple of posts on the forum from other people who have faced similar issues.
I am still waiting for GMAC to respond to my email. They seem to be making the most of their monopolistic hold of the market.
![Smile :)](https://cdn.gmatclub.com/cdn/files/forum/images/smilies/1f642.png)
If we were to contrast taking the GMAT at home with taking it at a test center, both options have their advantages and disadvantages.
Anxiety: I feel that taking the test at home tends to reduce anxiety, but doesn't eliminate it completely.
Noise: This is something you can't control. In my case, some construction work started next door just as I was starting the verbal section; this was extremely distracting and might have cost me 1-2 points. All things considered, at home you have greater flexibility to choose a slot that is silent (early morning / late evening).
Convenience: Considering the current pandemic situation, taking the test at home is way more convenient than taking it at a test center.
Whiteboard and markers: Take a look at the master thread on the forum. You should be able to find links to everything on Amazon. Also, during my exam, the proctor was more concerned with whether I was erasing the whiteboard properly than the make of the whiteboard and marker.
Conclusion: the GMAT (Online) is still my preferred option in the current pandemic situation.
My recommendation would be to assume that you will score 10-20 points lower than your average mock score and prepare accordingly.
Also, if you are using a slow computer, try to get the hardware upgraded. Upgrade your Internet connection, if required. Beg, borrow, steal.
TL;DR: GMAT (Online) is preferred. Assume a score drop of 10-20 points from your mocks. Upgrade your computer and Internet connection.