Video card

I've gotten the bottleneck calculator to work before with the E8400.

Edit:  Or so I thought.  I see things got switched to the Q8400:

Intel Core2 Quad Q8400 (Clock speed at 130%) with NVIDIA GeForce GT 1030 (Clock speed at 120%) x1 will produce only 0.87% of bottleneck.

Switching from an E8500 to a Q9650 yields 57% better performance according to game-debate.

More noticeably, increasing RAM and switching to an SSD really does breathe new life into an older machine.  16GB RAM is max listed for the 780.

Well, options were presented.  Whatever you want to do is up to you.

Screengrab below will show when  approved by a moderator.  It takes longer on the weekends.

https://m.youtube.com/watch?v=5Xo2gHb_qUw

Not sure what you mean by checking processor or whole motherboard.  Before changing CPU's it's suggested you make sure you latest version of BIOS for your 780.  Dell Command Update  Dell Drivers & Downloads 

In an earlier post, redxps630 said you needed at least 3GB VRAM on your GPU.  The GTX 750 ti has 4GB included in it's VRAM options.  "GTX 750 ti 4GB" can be used for a search term.  52GB also came up, you'll see it on the screengrab below, but I think they meant 5.2.

I think you meant have to replace the whole MB (motherboard)?  Nope.  Just the CPU if you go that route.  Remember new thermal paste between heatsink and CPU.  See YouTube videos if needed.

The post where I said I've gotten the bottleneck calculator to work before with the E8400 - I edited it.

@bradthetechnut 

thanks a mil. as i am not a hardware guy, one question:

Switching from an E8500 to a Q9650 means checking just the processor or the whole motherboard

In case you wondered in the midst of this, I did get the E8500 to come up with the GT 1030 2GB In GPUCheck (an alternative).  It said less than 8% bottleneck.

@redxps630 @bradthetechnut @donm4599x @speedstep

i just went to the PC parts shops, all declined to upgrade citing "old model" not up-gradable even just quad core processor not available. they are ask to assemble a new one.

the approx cost for an assembled one is $1100/-

i am lost...

For those who like to quote PC builds bottleneck calculator including myself, it has certain bugs occasionally so be careful. For example when calculating bottleneck result for i7-2600 vs i7-2600k matching RTX 2060/2070 etc., the calculator erroneously favored the 2600 and gave it a high pass no bottle neck while significantly criticized 2600k for severe bottleneck. That makes no sense. So always use common sense on top of calculator result when presenting results to other user for recommendation.

Do it yourself or expect to be ripped off by contractor.

Redxps630 is right about PC Builds.  Sometimes they say 100% bottleneck.  If it doesn't make sense, like one step of a CPU or GPU away and bottleneck was much better for one example, I then go with GPUCheck.  Or if I can't get a combo to work in PC Builds, there we go.

780 MT Service Manual  Replacing the CPU is on pg. 47.  I searched using "processor."

The heat sink and shroud - easy to remove and it'll be in the manual.  Even if I'm over-sharing, you shouldn't have to remove the big and shroud.  Did it on my previous 755 so I could clean the fan.  I had to cut off a tab with dremel.

Different model (745) but same chassis - YouTube CPU Upgrade  Includes RAM and GPU.

@bradthetechnut @redxps630 @donm4599x @speedstep 

you guys have been great and you all took time out for my post. i wasn't expecting that there would be much replies and so much guidance.

as here locally there is not much chance to get the processor, could either of you help with the amazon link to the upgrade processors so i could order.

as my dell has 4 x 2 GB ram, how could i replace it by 16 GB, if any link on amazon

and finally the GPU... its 99% for watch 4k large gig files.

thanks so much to all 

@Eyeson,

Thanks for the unexpected kudos.

Two posts above, I meant to say ...shouldn't have to remove big fan and shroud.

I suppose no eBay in Saudi Arabia?  You're welcome to for all the answers.  I burned some midnight oil last night.

Amazon Q9650 

I'm going to have to let someone else link RAM and GPU.  Amazon isn't as good at searches as eBay.  I won't link RAM unless it specifically list the models it's for.

I take it you wanted the GTX 750 ti 4GB?  As that one had very low bottleneck with the Q9650 and has the 4GB VRAM you need.

Q9650 eBay List  I noticed some things ship from China.  I don't know if that's a plus for you or not.

RAM List eBay  You'll have to pay attention  as other RAM also came up.  You might have to get two 8GB kits.  A-Tech has a lifetime warranty and I used it in my previous 755 to replace failing Hynix.

Crucial (crucial.com) RAM, with it's lifetime warranty and it being guaranteed to work in Dell's, often comes recommended by a couple of our Rockstars.  In this case, it's off of my recommendation list as they still show 1,600MHz RAM for the 780 on their website.  780 can take either 1,066MHz or 1,333MHz RAM.  1,600-(speed) didn't work for another user.  From the Tech Guide:  NOTE: This system supports both 1066MHz and 1333MHz DDR3 memory, however the memory will operate at 1066MHz speed due to chipset specifications. 

GTX 750 ti 4GB.eBay  Shipping from Israel.  Looks like a good seller.

Please remember you can also do your own searches.  If you need any further tips or help, please let is know.