Ok, story time:

Your graphics card is actually several hundred (sometimes thousand) unique processors tied to many different banks of ram.  They group the gpu processors into packs of 12.  My guess is that you either have a portion of RAM on your graphics card that goes bad under heat, or a group of processors that aren't being cooled properly.  You could try beefing up the cooling on your GPU, but if it's a desktop computer, I'd just replace your graphics card.

If it's a laptop, then either call in warranty on it.

That is my guess.  In any case, a problem that doesn't show up until 30 seconds after boot is always heat-related.  Could be heat in the monitor still, but GPU seems a bit more likely.

On Fri, Apr 29, 2016 at 9:06 AM, Michael <bmike1@gmail.com> wrote:
turned on the computer and no lines. after about 30 seconds they starte. I wiggled the hdmi cord but that had no effect on anything. I then considered that maybe the card unseated itself somehow so I took the card out and put it back in and turned the computer on and cooked an egg but the lines didn't start flickering again. Thanks for spurring me on guys!

On Fri, Apr 29, 2016 at 11:20 AM, Steve Litt <slitt@troubleshooters.com> wrote:
Also, be sure to wiggle the monitor cable at both ends and the middle,
while observing whether the green lines change. They could be caused by
a bad monitor cable, or a monitor cable that's not tightly screwed in
at the monitor or the computer.

SteveT

Steve Litt
April 2016 featured book: Rapid Learning for the 21st Century
http://www.troubleshooters.com/rl21


On Fri, 29 Apr 2016 00:03:21 -0700
Todd Millecam <tyggna@gmail.com> wrote:

> Straight green lines usually means either a bad monitor or a bad
> graphics card.  It could be a driver issue as well, so reinstall your
> graphics card drivers first and if the problem persists, try a
> different monitor on the same port and replace either monitor or
> graphics card accordingly.
>
> On Thu, Apr 28, 2016 at 9:47 PM, Michael <bmike1@gmail.com> wrote:
>
> > After post green lines appear on my screen. I thought it may be
> > related to an update I ran just before this started happening but
> > it happens even with a live disk. Is the computer hosed? I wonder,
> > about a week earlier I put an HDMI card in but everything has run
> > normally for a week or two so I don't think that is the problem.
> >
> > --
> > :-)~MIKE~(-:
> >
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>
>
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