My first guess is that if you have the original PSU installed it is not enough power for those upgrades. The original PSU was somewhere around 240W I believe. Also that system was never certified for the i5-3570. And I have not seen a BIOS update that allows for 3rd generation CPUs in the 390.

390 SFF , dead.? NO CASE SIZE TOLD. of the many.  but CPu  answers are below:

WHY read the benchmarks pages on what works.? (I looked for you , none there of 1000's)

the dell spec sheet shows gen2, only (back then long long time ago.

the H61 Express Chipset  ,  by Intel shows  what it can do (and wins all arguments first)

shows it can support gen 3, as seen here.

then you failed to upgrade BIOS first. this is a big error, and dell does not document what bios upgrades do,

only the most, limited terms, (near useless docs) but this was first, and now you got to put the old CPU back and then burn new BIOS, and try again.

now the bench markers. over 6000 deep, in fact now.

i5-3570 ,,   59 pages there. (I see no GEN3)

but if I try to build PC there with 390 it fails with your 390,   so 6000_ I did not get it to work if tried.

they do not report failures, there ,  just pass.

I say no..   but if the mobo  will not take it , all is lost.  (why not get used 3020mt or 9020mt and use that)

Gen4 Haswell up! and win.

a far far better PC, mine cost me $50 , sell yours get $50 dollars in hand and upgrade the whole thing,

NO PC told yet just the near useless 3 digit code 390,  PC.  MT, DT< SFF, USF micro AIO. 

never post lacking such a key fact or photo of  you PC, oK  unless you like wrong answer or 5 answers, 1 right.

1050 TI uses 75w and you have LESS THAN 300W power supply so you have fried your power supply.

GT1030 low profile is the only card that works.

https://www.youtube.com/watch?v=2y32mBdZHJY

https://www.dell.com/en-us/work/shop/msi-gt-1030-2g-lp-oc-graphic-card-2-gb-gddr5-pcie-30-x16-low-profile-hdmi-displayport/apd/aa362018/graphic-video-cards

Hi @speedstep,

Instead of frying power supplies, would the 315w XE2 SFF PSU work in the 390 SFF?  I imagine a 24-pin to 8-pin adapter might be needed?

Would buying an XE2 would be more worthwhile?

yeah looks like it was the cpu, i did update the bios a few months before like i said i didnt see anything about 3rd gen support but figured id try anyways.

it has a 250watt psu, which yes is pushing it a bit. and i said the computer still turns on, if it was fried it wouldn't do anything at all. and after taking the new cpu out its working fine with the 1050ti for the moment, so not sure what your on about.

it is yes, 250watt, and i took the cpu out and put the old one in that was the issue.

and the 1050ti is working great in the computer for the moment

Optiplex 390 Tech Guide 

https://www.ebay.com/i/260758966750?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=260758966750&targetid=596843717518&device=m&mktype=pla&googleloc=1028087&poi=&campaignid=2086088304&mkgroupid=77258593396&rlsatarget=pla-596843717518&abcId=1141016&merchantid=6583194&gclid=EAIaIQobChMIxsjXqfqB5wIVjIbACh3irgEuEAQYAyABEgJlCvD_BwE 

https://www.ebay.com/i/291616153876?rt=nc&_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D1%26asc%3D40741%26meid%3D4ac1c6fc440849c3b229068852f7b7fe%26pid%3D100694%26rk%3D2%26rkt%3D30%26sd%3D260758966750%26itm%3D291616153876%26pmt%3D0%26noa%3D1%26pg%3D2386202 

A couple of links above for possible PSU upgrades.

In the description for the first link, it says "NOT FOR DELL OPTIPLEX 790 990 390 SFF CCCVC."  I don't know what that's suppose to mean.

A possible catch with the 2nd link - it says "slimline" but not "SFF."

PSU upgrades for DT's and SFF's are normally hard to come by.

Good to hear your PSU isn't fried.  If speedstep or another expert answers my questions about the Optiplex XE2 315w PSU, you still might want to consider it.