Samsung 305t
Max resolution ( it’s “Optimal” or “Native” resolution, at which the display looks best set to)
2560 x 1600 pixels at 60 Hz

As in , ONLY at 60 Hz.

What vertical refresh rate do you have it set to ?
If you have that set higher than 60 Hz, if you get a display, you will probably get video symptoms and doing that can DAMAGE the monitor !!!

If you have loaded the specific drivers for the 305t, when you RIGHT click on a blank part of your main desktop screen, and choose Personalize – Display Settings, for the display icon for the 305t, it should show Samsung 305t or similar on (the name of the display adapter.)

If you do NOT see that, then your monitor is probably using Plug n Play monitor drivers, and you can set settings that your monitor does NOT support.

When Windows is using the specific drivers for the monitor model, by default, Windows will only show you settings that the monitor model supports, however, it’s possible to over-ride that and in that case it’s possible to choose settings your monitor was not designed to use,.

Whatever computer you connect the monitor to, you must have NOT set the monitor to settings in Windows that it wasn’t designed to be set to. Doing that can produce video symptoms that it wouldn’t otherwise produce, or even DAMAGE the monitor’s circuits or display.
…..

“-Monitor is going bad (though not sure why it would not produce the same artifacts on the other computer, possibly because it was at much lower resolution?)”

If the problem monitor does not produce the symptoms when it’s connected to a different computer on which you can set the settings to 2560 x 1600 at 60 Hz , there’s nothing wrong with the monitor
E.g.You could connect it to a desktop computer that has a video adapter than CAN support that resolution, or (a lot more work) remove one of the two video cards and install it on another desktop computer that has a power supply capacity that can support it , install the drivers for the card, and try the Windows settings set to 2560 x 1600 at 60 Hz

If you DO get the symptoms when it’s connected to another computer set to 2560 x 1600 at 60 Hz,
NOTE that sometimes the board(s) on a monitor can have one or more failing electrolytic capacitors, and if it/they are replaced before they have failed completely, the monitor will work fine,

What to look for, mboard symptoms, example pictures:
http://www.badcaps.net/pages.php?vid=5
Home page that site
– what the problem is caused by
– he says there are STILL bad capacitors on more recent mboards.
http://www.badcaps.net/

Pictures of blown capacitors, other components, power supplies, fried Athlon cpus, etc.:
http://www.halfdone.com/Personal/Jo…

E.g. I fixed an LG LCD monitor by replacing two capacitors. NOTE that you should at least replace all capacitors of the same mfd capacity as the one(s) that failed that was made by the same brand, because they are just as likely to fail. Ideally, you should replace all capacitors made by the same brand as the one(s) that failed that has a 330mfd or higher capacity.

“-drivers are causing some issues (why would the other two screens not show the same problems?”

Since the two video cards have the same Radeon video chipset, the other two monitors have no problems, there’s probably nothing wrong with the video drivers.

“-Motherboard has some issues perhaps?? (I haven’t seen any problems in the screen while booting, but perhaps something fishy is going on with the circuitry that is causing some issues? doesn’t seem likely but throwing it out there)”

The mboard can have damaged circuits, or one or more mboard slots that a video card is plugged into can have damaged circuits, or one video card can be damaged but not the other, but since you say the symptoms appear on the problem monitor no matter which of the two cards you connect to, it’s probable that none of those things are damaged.

A video adapter can be damaged such that it works fine in plain VGA mode, e.g. while booting the computer before Windows loads, or in Windows Safe mode or in Enable low resolution mode , or in Windows when the specific drivers have been NOT loaded in Windows for it, but NOT work fine when the specific drivers HAVE been loaded for it in Windows,
– or, rarely, it may be damaged such that you get no plain VGA video from it but it does work AFTER Windows has loaded when the specific drivers HAVE been loaded for it in Windows.

…but you say there are no symptoms on the problem monitor BEFORE Windows loads and that it has video before Windows loads and the other two monitors work fine connected to either video card, so that’s not the problem.

“-Problems from my power supply, capacitors perhaps? came with my case, and about 3 years old. Voltages seemed within range, no other issues (such as self shutdown) noticed”

Problems with power supplies are common.

Check your PS.
http://www.computing.net/hardware/w…

You mentioned the voltages seem to be okay, they must be within 10% of nominal, but is/are the fan(s) for it working properly ?

I don’t recommend Cooler Master PSs…

A friend of mine had a problem with a 600 watt Cooler Master PS.
When I was working on his system getting rid of some software / malware problems, I noticed the top of the desktop case was getting really hot, and I found the PSs single fan was not spinning. It was less than two years old., and the 3 family members that use the computer it was on normally only use the computer in the evenings when school and university is in session.
I replaced the fan but the PS failed to boot the computer a short time later because the PS had been damaged from overheating for who knows how long. The same PSs fan was working fine when I worked on the computer a few months previous to that.
When I looked up it’s model, I found it had only a 1 year warranty (not found on the Cooler Master web site – only found in ads for the model), and that others had reported the fan had failed.

I also found when I searched that some other Cooler Master models have only a 1 year warranty, some are known to have premature fan failures, some are known to develop failing electrolytic capacitors.

Try searching the web with your specific model to see if you can find mentions of problems with it.

Try a known good used PS with it, if you can, one from another computer you have, or from a friend’s computer, that has enough capacity (see next).
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ATI Radeon™ HD 4890 Graphics System Requirements
http://www.amd.com/us/products/desk…

500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode)

Your PS capacity of 1000 watts is a lot more than the recommended minimum 600 watts for two 4890 video chipsets.

Each card must be connected to two individual PCI-E 6 pin (male) power connectors. The PS must have 4 of those coming from it’s wiring.

NOTE that….

If it does not have enough built in PCI-E 6 pin power connectors…..

– DO NOT use a Y wiring adapter – one PCI-E 6 pin (female) to two PCI-E 6 pin (male) – it probably can’t supply enough current at +12v to the card. (You may only have problems because of that when the video chipset has more of a load on it, such as while you’re playing a high end game.)

– you CAN use individual molex 4 pin (female) to PCI-E 6 pin (male) Y wiring adapters, connected to two spare 4 pin molex (male) power plugs.
e.g.
http://www.xpcgear.com/6pinpciexpre…