Tried upgrading optiplex 780 ram, wont turn on

What is the size of RAM sticks already installed?  Does the Crucial RAM replace previous RAM or is it in addition?  What size are the Crucial RAM sticks?

You could try one Crucial stick at a time to see if the new RAM works.

You probably haven't seen one of the RAM speeches so here it goes...

Particularly in some older Dell's such as the 780, RAM sticks need to be matching in size, brand, and speed is helpful too.  Crucial does come regularly recommended by a couple of our Rockstars as it's guaranteed to work in Dell's and has a lifetime warranty.  You did good with avoiding Kingston Value RAM (KVR), which rarely works in Dell's.  (Regular Kingston is ok.)

Just in case, remember to unplug PC anytime working on the inside of it.

By any chance did you update PC to the latest BIOS before installing new RAM?

Was your size 2032 CMOS battery replaced within the last 5 yrs.?  It's often a cheap troubleshooter as a low battery can cause all sorts of bizarre problems.

Optiplex 780 Tech Guide 

It currently has 2 sticks of 2 gig in it right now, I finally got the dcomputer to get past the beep code stage. Now its saying the computer is onlying running 2 gigs.Have not updated BIOS, or changed battery, I just bought this used  about 2 months ago.

I went with crucial cause i seen a few posts that state crucial works well with dell. So thats what I chose. $140 I paid.

2 - 4GB DDR3L-1600 UDIMM 1.35V CL11 SR

Thats what the new ones are im pretty sure. I think I might of ordered the wrong ones. I thought mine was the desktop but i guess its the mini tower. THE RAM currently installed is 2 sticks of 2 gigs. 

I Uploaded a pic of  a new stick and an old stick.

that sounds like a lot you paid for the ram or computer or both?  this is a relatively old optiplex and I have had a few in the past (MT and SFF).  The MT uses standard ATX 24 pin whereas the SFF uses mini ATX 24 pin.  One of the good thing in this model is it supports 45 nm core 2 quad including Q9650 if the motherboard has the correct P/N.  imo no need to get special ddr3 sticks for it.  any regular major name brand 2-4 GB DDR3-1333 (PC3-10600)  would do, such as Samsung, Hynix, Elpida, Micron, etc.  I would say a complete system with hdd running Windows 10 should be around $75 on local CL.

spec MT/DT/SFF- Four DIMM slots; Non-ECC dual-channel 1066MHz or 1333MHz DDR3 SDRAM, up to 16GB maximum system memory

I take it you're using the original RAM and it's only seeing 2GB. Now it's running and boots into Windows?  I still suggest changing the CMOS battery, now especially since the 780 was bought used.  (The 1st thing I had to do on a refurbished 790 was change the low/dead battery.)

Update BIOS if it isn't on the latest version for your 780.

I just saw the above replies.  I was working on this when the power went out.

Hynix failed me when I had a 755.

Yours is the MT (mini tower)?  Image will appear below once approved by moderator:

I have the mini tower. I ordered for a  desktop. But i checked and im pretty sure theyre both the same that crucial was selling. Someone told me to get DDR3 and not DDR3L. Maybe that has something to do with it. Currently my computer is running back to normalat 4 gigs. I was just gonna add the 8 gigs to the 4 gigs. I dont really know im doing lol

I updated bios to a15, Tried just one ram stick, stkll nothing. The numhers 3 and 4 were lit up in the feont

Helps of you're a little more specific.  Was this a Crucial stick of RAM you tried by itself?  By any chance have you tried both Crucial sticks in the same slots in which the original RAM was working?

If you can't get either Crucial stick to work, but the original RAM works, then may be you do have the wrong Crucial RAM.  Sorry to see you have such a hard time with it.

I checked the Crucial site.  It looks like the same RAM for the MT and the DT.  I'll have screengrabs below.

Unfortunately, I couldn't tell much by your photos.  Reason being is because I can't expand them on my phone to see the fine print on the RAM sticks.  May be it shows up better on a PC.  Phone is my only home internet.

Remember my RAM speech?  Have you tried running just the Crucial RAM in your PC?  Remember, chances are mixed RAM won't work in a 780.

Though you planned on 12GB total RAM, you'll still notice a difference in performance going from 4GB to 8GB.

EDIT:  Screengrabs below will show 1,600MHz RAM, which is what came up on the Crucial site for the 780.  The 780 takes either 1,066MHz or 1,333MHz RAM.  Images can't be deleted.

Images will show once approved by a moderator: 

MT RAM

DT RAM

the old ram is PC3-10600 which is DDR3-1333, as it should be.

the new crucial ram is DDR3L-1600.  it is a bit too fast.  maybe that is why it would not work.

I 2nd that.  Pasted 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.

When doing searches on Amazon and eBay, both 1,600MHz and 1,333MHz RAM comes up.  Not sure why when 1,600MHz is the wrong speed for the 780.  It would seem some suppliers try to tote the RAM for too many Dell models.

https://www.amazon.com/Dell-Certified-OptiPlex-Desktops-SNPY996DC/dp/B005CPU56M/ref=mp_s_a_1_11?dchild=1&keywords=dell+ram+for+dell+optiplex+780&qid=1588215074&sr=8-11 

I'd link some RAM from eBay, but online eBay reverted to the app on me.  I'm sure you can also search anyway.

If your Crucial RAM is 1,600MHz and isn't working, you should be able to return it.

I'll be editing my post above with the screengrabs.

I also noticed the differences  before I bought, I webt against my guy and said no crucial should be right.

They are not backing down saying the ram is compatible. Thanks for all your answers, im sure ill be back later when i buy the wrong ram again.

I didn't realize 780 MT used sodimm memory.

@Brokecomputer  Did crucial refuse to refund your money?

If you can return it, you might want to look at used memory (of any brand). It will also be MUCH cheaper than new (especially crucial). I've had good luck with several brands, and also mixing them in the same system. They all have the same basic specs though (except different sizes).

I contacted Crucial myself through their website and below is what I was emailed back.  They still need to fix it on their website, which I already informed them.

"Dear client,

thank you for contacting Crucial, it will be a pleasure helping you.

Regarding your question, we would like to inform you that your system supports only DDR3 SODIMM module 1333Mhz.

In case of any questions or doubts do not hesitate to contact us.

Regards

Georgi
Memory and Storage Expert
Crucial by Micron®
Micron Consumer Products Group
Contact us: https://www.crucial.com/support/contact"

By the way, I didn't know the 780 used SODIMM RAM either.  Interesting...