Projector comparisons

What is your budget? Does the 4K to 7K include the screen? Does your room have complete light control? What size and type of screen are you considering? How far from the screen will you sit? These are some of the considerations that influence your decision. AVSFORUM has an active Display Devices section including over $3,000 and under $3000 projector forums.

As a few have mentioned, JVC and Sony are generally the manufacturers considered for a quality Home Theater Projector.

Sony just announced a couple new projectors so you may find some used options for owners that like to upgrade often. I wouldn't go back more than one generation for used and would want native 4K support.

JVC hasn’t released anything new for a couple years but are still favored by a lot of users. I have owned JVC projectors and currently use an RS-JVC 500. It can play 4K and HDR content but is not native 4K as the current RS3000/NX9 - JVC RS2000/NX7/N7 - JVC RS1000/NX5/N5 models are. If I was to upgrade I would go with the JVC RS2000/NX7/N7. I also have a Lumagen Pro processor that adds a lot of cost but can really dial in a calibration and has excellent Dynamic Tone Mapping.

For longer HDMI cable runs consider RUIPRO Fiber Optic HDMI Cable, Supports HDMI2.0b,4K60HZ, 18Gbps Bandwidth, HDR10, Dolby Vision (various lengths from 6m to 30m).

I'm now on my 7th projector since getting into home theater in the early 90's. In the mid-90's, I was feeling flush from an investment that paid off and bought a Vidikron Vision One and Snell&Wilcox video processor - total investment about $100K, plus the cost of a fancy screen. At the time, this was the best of the best. (Fortunately, I was able to see the system at a reasonable price to the person that bought that house from me a few years later).

The Epson 5050UB projector I bought recently for under $3K delivers significantly better performance - MUCH brighter, better resolution, better shadow detail, no convergence problems, lower audible noise, much better uniformity across the screen.

Projector technology is changing as fast as flat screen TV technology. If I was you, I'd invest in a really good screen, since this will last you over multiple generations of projectors. A quality fixed-frame screen will run you between $1500 and $3000. If you want retractable or electric masking, the cost will go up a fair amount. Don't skimp on the quality of the screen. 

I'd recommend against getting a used projector. Not only is the technology changing fast, but you have to worry about compatibility with new content and equipment, and they don't last forever. You'll almost certainly need to replace the bulb in order to get full performance, and will probably have to have it thoroughly cleaned to eliminate the dust that accumulates inside. And you probably won't have any warranty. Given the projector quality you can get for the money these days, it just doesn't seem worth it. For under $3K, you can get a stunningly good projector.

What are the minimum specifications for a laptop to process 4k video for a projector? I am considering new models of high resolution projectors. But I have doubts about the laptop: core i5, 8 Gb RAM, nvidia 630m 2 Gb.

@karlbee a new thread would have probably made sense for your question, but the laptop's manufacturer provided specifications should indicate what resolution and refresh rates it supports over any HDMI video outputs it has. That's the only way to be sure.

It really depends on what you're trying to do.  I don't think anyone on this forum knows enough about this particular subject to recommend.  You also have features such as HDMI 2.0 and Dolby Vision / HDR that your particular laptop may not support.

As far as laptop power goes, I would think that core i5 and 8 GB of RAM should be fine.  It doesn't require a lot of processing power to just playback 4K video (either from streaming or a bluray disc).

The PowerDVD software (which supports 4K) has minimum requirements here:

https://www.cyberlink.com/products/powerdvd-ultra/spec_en_US.html

Hope that helps.