Current specs are:
E8500/4GB/160GB HDD/On board audio video cards
I mainly use this DC7800 for web browsing, watching youtube, MS Office and documents, occasionally photo and video processing.
I am wondering if it's worth max the memory to 8GB and add SSD. Will there be any significant improvement? And how to transfer the Win 10 pro digital license to the new SSD?
e8500 doesnt work with windows 10.
But it is currently running Win 10 Pro.
How "occasionally" do you do photo and video processing? Because for web browsing and Youtube, there's no point in adding more RAM or an SSD. You'd either stay with this one, or just buy a complete new box because the E8500 is honestly ancient.
You're better off replacing. The upgrade to 8GB won't do much but the SSD will definitely make it a lot faster. As others have said, E8500 isn't officially support by Windows 10 and will be a bottleneck.
Another thing to consider is that the PSU is 240w so if you ever wanted to add a video card further down the track then you'll need something very old as many cards have a 300w requirement.
I had the same box, HP DC7800, originally with 2GB RAM and then 6GB RAM on Vista 64-bit. Am now running a HP DC7900 Core 2 Quad 2.66GHz that I picked up for $30-$40.
Its definitely NOT worth spending anymore money on the Core2Duo HP DC7800.
Increasing the RAM from 4GB won't make a difference for YouTube + Word processing. The current speed bottleneck will be the dual core processor. You can verify your RAM usage with Windows built in Task Manager, [Ctrl]+[Shift]+[Esc].
Video processing and RAW Photo editing is so much more quicker on a quad core processor. If given the choice between RAM or CPU (Core2Quad) then I'd put the money towards a faster CPU and keep the 4GB RAM.
My Core2Duo could only play YouTube videos at 720p. Whereas the Core2Quad can play YouTube videos up to 1080p (Firefox + VP9).
I wouldn't bother running Windows 10 on a Core2Duo. Windows 10 has sooo many background processes (eg. Cortana, file system indexing, etc) that it will slow down your dual core processor heaps more than Vista/Win7. Would be much better to consider switching to a light weight Linux operating system (eg. Lubuntu), that's if you have to stick with the HP DC7800.
Better to upgrade IMO. E8500 is getting pretty old now.