Help? Bad PSU -> Fried GTX 770 -> 100% Fan & No Display message - Page 1
Forum section: electronics / repair

author: Drainaway
author_rank: Newbie
timestamp: February 21, 2018, 06:11:40 pm
content: Goodmorning everyone!I'm a new member of the community and this is actually my very first post in this forum, but more than once in the past I've found help here in your discussions, and now that I'm completely without ideas about my problem the must ask for direct support to youI have a VERY LOW BUDGET PC, made with a server motherboard, a GTX 770 for gaming and two PSUs, one for the motherboard and the HDD and one for the GPU and the fans.Tonight the PSU that powered the video card flickered for a couple of seconds before turning off (after further inspections I found that I had not properly connected the PSU plug on the wall) and after having fixed the power supply and restarted the computer I found the first damage to the video card: 100% fans and no video output.I immediately tested that the motherboard wasn'd damaged, which works both with the integrated video card and with any video card that I have tested with, and I was able to borrow a pc from a friend to test the GTX 770, which gave the same problems: 100% fans and no output.The card is not detected by windows in device management if i boot with the integrated GPU, nor from NVFLASH, unless i unplug the pci-e power cables.In this case the VGA communicate with the PC, and the output that comes out is the typical message "please power down and connect the pcie power cable (s) for this graphics card", leaving me hope that the card is not definitely dead.Same with NVFLASH, it correctly recognise the GTX770 only if no pci-e power cable is connected (but i can't manage to flash the new bios in it, probably just because there's no power cable plugged)Now, my problem is that i can't find any problem on the PCB with my knowledge alone, so i must ask you for help.In the image i marked every mosfet and voltage regulator i can find, and the readings of the fuses on the left (that makes me think that they are ok).Any help will be greatly appreciated /:)

author: Rasz
author_rank: Super Contributor
timestamp: February 21, 2018, 10:05:55 pm
content: full fan no display is a sort of protection mode of card power controllerlooks like palit jetstream?check R52 53

author: Drainaway
author_rank: Newbie
timestamp: February 22, 2018, 01:17:12 am
content: Gainward Phantom, 4GB model.Both the r52 and the r53 are showing 0.002 with some fluctuation - probably because my multimeter battery is too low.I will retry as soon as i change the battery.

author: Jwillis
author_rank: Super Contributor
timestamp: February 22, 2018, 02:44:15 am
content: Hello and welcome. The R12 1332 are 120 nH (nano Henry) inductors marked on board as L7(hard to read that one),L8,L9,L10,L11,L12. The one with the R and X are PFC (Power Factor Correction ) inductors marked on board as L16,L17 and L13,L14.The one in the top left is probably one as well but I can't read the board marking.Those with the letters should have 4 connections. All connections on any inductors should have very low resistance but as long as they are not open they should be Ok.

author: Rasz
author_rank: Super Contributor
timestamp: February 22, 2018, 04:53:32 am
content: Quote from: Drainaway on February 22, 2018, 01:17:12 amsame company same Palit GeForce GTX 680 JetStream pcbQuote from: Drainaway on February 22, 2018, 01:17:12 amthey are fine-buzz molex connectors to power transistors continuity-buzz mosfets for shorts maybe, altho short would probably not let it start at all?-trace what is measuring r52 r53, those are used for power consumption estimation, possible controller is using those to check if both cables are pluggedThere are few options-something other than fuse failed between molex and transistors, card really doesnt get 12V from one of the molex (it wont start with only one)-power controller chip cant see the power applied and goes into protection mode (fan full blast).-power controller chip partially failed due to 12V spiking over its limit-one/or more of the transistors died, luckily power is divided into pcie slot/molex connectors sections, thats why card is able to start with nothing plugged in low power "warning" mode.>PSU that powered the video card flickeredalso get rid of that power supply, its protection circuit must of failed to cut off 12V during bad mains power