Unknown issue with PC

[Halororor]

Okay, seeing as Skyrim is going to require me to plug my graphics card out to be able to plug my DVD Rom in, I might as well see if I can't resolve the issue before then.

 

Something in my PC is causing issues, and I have no idea what. It's been doing it for years, all the way through upgrades and overhauls, and it's got me stumped.

 

Often after my PC has been in transit, or when I install a new graphics card, I have issues getting the PC to work. I'm not sure if it's my PSU, motherboard, or what, as it's been doing this since 2009. Since then, I've had two new graphics cards, a new motherboard, new CPU and a new PSU, and the problem still persists.

 

What happens is that I'll install the GPU (or try to switch the PC on after bringing it home), and then the PC receives power, but doesn't do anything. It powers up, the fans start spinning, but the hard drives don't initialize and it doesn't seem to POST. The screen goes into Standby mode.

 

When I remove the GPU and use the on-board GPU, there's about a 90% chance it doesn't happen, and when I replace the GPU, it more often than not happens again. Now I know this sounds like it's an issue with the GPU or PCI-E slot, but I'm not quite sure, seeing as the exact same thing happened with two different GPUs and another motherboard.

 

I'm not sure I can blame the PSU, because it's a 550watt PSU, and my HD6870 requires only 450, so there's enough output for the system. I'm very hesitant to blame the PCI slot, because once you get the card working, it stays operational until you move the PC again or remove the card.

 

The only solution I've found so far is to unplug absolutely everything in the PC, and plug it back in, then try again until eventually the PC starts up. As you can imagine, this is highly frustrating due to the fact that it's not a set solution and when I had to install my GTS250 in December it took me about three hours to get it working.

 

Skyrim is coming on Friday, and my HD6870 is such a large card that it obscures all my SATA ports, leaving me without a DVD Rom unless I remove the card. Unless my flatmate is there to make an image of the disk for me on his PC, I'm going to have to unplug my card to get it installed, and I'm probably going to spend the next three hours after that trying to get the PC to work, which will kill me.

 

Anybody have any idea at all what might be causing this?

[bben46]

1. You say:

I'm not sure I can blame the PSU, because it's a 550watt PSU, and my HD6870 requires only 450, so there's enough output for the system.

That leaves only 100W for everything else in the computer. Kind of marginal. It's possible that there is a surge on powering up going over the 550w just a little - and if your PS makes it past that the power requirement drops down to a tolerable level.

 

I recently saw a test of various power supplies and many could not put out the power that was on their data plate - especially the no name inexpensive Chinese supplies.

 

A suggestion is to somehow delay the case fans for a few seconds on power up - as fans pull more current to get started than when they are running. Do NOT delay the CPU or GPU fans though. Note that once a fan is running it draws very little power probably in the tenths of a watt range.

 

Here is a link to how to size a power supply. http://extreme.outervision.com/psucalculatorlite.jsp

 

2. Sounds like your MB is poorly designed for that Graphics board. You might try to find some SATA cables with right angle plugs if you have just a small gap under the board when it is fully seated. - My MB came with right angle SATA cables so they do exist. :biggrin:

 

3. You say

after my PC has been in transit

It could be that one of the boards or some other component has been shaken loose. If you can feel a board move just a little when pressed down this could be the problem. If there is just a small amount of moisture on the connector, MB or PS - caused when moisture accumulates when taking a cold computer into a warm room, it can prevent starting until that moisture evaporates - allow the computer to reach room temperature before powering up. Also, if the system is completely cooled down, a sticky fan may take more power to start and run (a small surge) until it warms up a little. I have seen a fan hesitate for a few seconds before starting then start jerking and finally run. If you see this, that fan is drawing much more than normal current trying to get started - Replace that fan. :thumbsup:

 

4. As you seem to be messing around inside the case, I assume you have cleaned out at least the obvious dust. Check the air channels on your Video card to make sure they are clean and the fan can spin freely. Also, the heat sink fins on the GPU for dust slowing the GPU fan - some motherboards shut down if they do not detect a GPU fan running withing a few milliseconds. - That's what that 3rd wire on the fan cable is for - just to make a fan run only requires 2 wires. If it has 3 it can at least detect the pulses from the fan. If it has 4, it is probably a variable speed fan that can change speed up as temperature increases.

[blove]

Cold solder joint, loose pin in a socket, or a broken wire are a few other culprits. Since it happens after moving, I would suggest checking the sockets for things like out of place teeth, foreign objects, and pins that are too short or too long.