[Question] Different SERP results in different computers?!

Yeap, I'm having the same old problem again.

I checked SERPBook.com and it showed that my site is ranking first for a very competitive keyword.
But when I check in my computer using Chrome's incognito mode, my site wasn't first but at the 5th page (45-48th position).
Checked my rankings in one of my old VPS located at Canada, it shows 7th page (68th-70th).

So who to trust?

And yes, I've logged out, cleared all cache, and even use incognito... so I'm NOT logged to google account.

From my past experience, I thought this was caused by a lack of update/cache to other google servers; therefore, one of them is right, but just haven't update to the rest of Google servers.

So what do you think? There's a chance for it to go back to first, right?

There's nobody to fully trust nowadays, simply because G shows different results based on IP, browser, nearest data center, cookies, and etc... and etc..

It's like google is setting up an illusion to satisfy everyone and have control over what's popular or not!

seriously though, just get some friends or people on this forum to check your site from different places and check it manually, that way you'll have a good overview