What is the best 775 socket motherboard?

Within this link you'll find Optiplex's model years:  https://en.m.wikipedia.org/wiki/Dell_OptiPlex 

I could suggest:  Get an Optiplex 780 MB.  Then you'd still have to get the CPU & RAM.  However, Dell is so proprietary, I'm not 100% sure on that suggestion - close, but that's about it.

How's your budget?  You're overdue for almost anything newer.  A seller refurbished 780 can be bought for $50 from eBay.  A little more, and you can get a 7010.  With standard processor and RAM, a 7010 will run as slick as a topped out 780.

First 2 screengrabs are from eBay.  3rd is from Walmart app.

By the way, it's not said what size your GX620 is - MT, DT, SFF, or USFF?

Images will show once approved by a moderator.

https://www.ebay.com/itm/Dell-Optiplex-780-duo-core-tower-3-0GHz-2GB-ram-160GB-hdd-dvd-burner-no-os/202772979541?hash=item2f36361f55%3Ag%3AFTkAAOSwkGVZtFVf%3Asc%3AFedExHomeDelivery%2160193%21US%21-1&LH_ItemCondition=2500&LH_BIN=1 

https://www.ebay.com/sch/i.html?_from=R40&_nkw=optiplex+7010&LH_BIN=1&_sop=15&LH_ItemCondition=2500 

https://www.walmart.com/search/?cat_id=0&page=1&query=dell+optiplex+7010&sort=price_low 

Okay thank you so much.

so I have 4GB or ram at 533Mhz , do you suggest upgrading to 800mhz ? 

An SSD does breathe new life into older machines. My 755 has a 17 sec. boot time, programs instantly open, and so on.  The RAM increase and a quad CPU helped all of that as well.

Optiplex GX620 & GX520 Spec Sheet 

1.  Even if you could, your system would run the RAM at the slower speed.

2.  Being able to increase RAM capacity makes a bigger difference in speed than going from 533MHz to 800MHz.  However, it's not an option on the GX620 already being at 4GB.

That's why speedstep and I suggest or recommend anything newer for a PC.  The GX620 is too limited in upgrade options.  Almost anything newer gives you more options.

About the only GX620 upgrade you could do is add a GT 1030 gpu.  But I'm not sure that would give a noticeable difference in performance.

I definitely understand the fun in doing upgrades.  I had fun with my 755 MT upgrading RAM, CPU (quad), added an SSD, added USB 3.0, added a GPU card.  I wouldn't have been hardly able to do any of that with a GX620.

wrong post to 775 not 620

that case is non standard,  and only works with old dell motherboards,  for sure that very very odd crossways

CPU heatsink and very odd mounting that uses custom mount supports under that odd HS.

The best CPU must  be your question and is answered here.

and was asked many times here, if you search it is very well reported.

the non 130watt CPU is the answer.

here is the list of rules (simple and short) the lists is on the wiki, showing the series!

• must be supported in BIOS. (update it first)
• must be not use  the high powered 130watt CPUs.
• must match the chip set limits. yours is intel 945G chip set.  The G45 motherboard is far better !
• the dell max is Pentium® D 800MHz FSB socket T (per dell book)
• The chip set limit (not 130w)  is. Core 2 DUO ( quad not listed is max)
• the CPU limit for DUO is, E4700 , limited by 800MHz FSB. front side bus.  65watt.

sorry was gx620 not 775 optiplex ,

Intel® 945G chipset, Intel® Pentium® D processor with Dual Core architecture, Intel® Pentium® 4 processor with 800MHz front side
bus and Hyper-Threading and up to 2MB L2 cache or Celeron D® processor with 533MHz and 256K L2 cache,

4 DIMM slots (2 DIMM slots on USFF chassis);

Non-ECC dual channel shared2 DDR2 SDRAM system memory (533Mhz) up to 4GB  (minus 1/4GB for igpu)

2005

the chip set is designed only for: these classes, (note that quad is missing)

Pentium 4, Pentium D, Celeron D, Core 2 Duo (best)

quad started with CORE2, not 900 series P965 or   975x.  june 2006 up, 1 year newer chip set than yours.!

the 945 is old,  G means graphics iGPU inside.

GMA950 igpu is not supported by intel and at end of  this month, it ends for W7 too. at intel.

E6700 is max on this 945G. CPU number. is 65watt CPU. max.

"seems nobody hot rods 755, ever. for good reasons, ($500 saddle on a  $5 horse)"

More like a $100 saddle on a less than $100 workhorse I bought as a refurb 3 yrs. ago.  It whips everything including Win10 Pro and recording studio software.  It runs it seemlessly.  Some people can go ahead and judge it as "old," (it certainly isn't new), but it still runs great.  Speedstep also has a working GX620.  Certain generations of Optiplex's run a long, long time.  Instead of spending more on newer PC, budget allowed me to upgrade what I have over time and it worked out.

https://m.youtube.com/watch?v=8dfiMGZ0wzA 

https://m.youtube.com/watch?v=jK51T7IX8UQ 

https://m.youtube.com/watch?v=TqiU3JGl2R8 

I know what you mean Brad. I have an old mare about 30, still living. I had a stallion appaloosa till a couple of years ago that I shot with a 44 in the edge of the woods where the old boy went down. A very sad day for me.

Animals make me happier, and also sadder, than computers in plastic boxes.

Yah, if the 755 does go out, I know what I want and it has an I7.

I also have a 790 DT (seller refurbished for $50) running Win7 32-bit so I can use some of my software that doesn't work with 64-bit.  It has options some of my newer software doesn't.  And it works great with the HDD my 755 used to have.  Boot time isn't 17 sec., but runs everything else well.

This 620 has no value at all now,  not even worth $50

the mobo just sold on fleabay for $14 , free ship, working. so is free, (we call this bottomed out )

the limit here is :
what, that 945G chip set and 800mHZ FSB.

the core 2  with newer stepping runs ok (DUO) windows 10 64bit, with 4GB of ram (have one here doing that)

a better PC in this era 1 decade back is one with G43 G45 chip set not older, ok?

it is true CPU used go for 3 bucks on this old PC< that is because nobody does this, so CPU are dirt cheep

like the

I Have a 380 in the lab , testing it with the last processor ever made for it to work and work with 64bit, now.

I have 790 runs w10-64 fast,  with ssd .  even runs new super fast GPU cards and runs even 250 watt GPU.

The 790 to me is the bottom tier (today) IMO core i3up.

best?

1. the one that run a core2, quad is best, lga755, the 945G will (laptops 945gc will not)
2. the one that runs a Killer-app (unstated yet) that is only sold as 64bit only, (name it please?)
3. one that runs windows 32bit?, it does. xp to 10 sure does.
4. one that runs windows 10 64bit but will run slower than 32bit with 4GB of ram but if #2  , you must.
5. or you have better list?, why not define best?
6. The Q45? chipset mobo? like this?
7. or from dell ?, Q45 ! use these PC  Optiplex 780/XE/760/380/960, whole or in part. and more.
   
    
8. Vostro 220

   Vostro 220s

   Vostro 420 ( and more maybe too lazy to search dell 100% me. for all Q45 mobo.