Custom Resolution Utility (CRU)

[xod]

I have a HP monitor (model: w22) with native resolution of 1680x1050 and a preferred refresh rate of 60Hz. I had previously connected to it through VGA. I wanted to achieve a refresh rate of 50Hz for Amiga and NeoGeo emulation, and various sub-60Hz freqs for some MAME supported arcade systems. As the EDID apparently reported a vertical frequency range of 48Hz-76Hz, but I was unsuccessful to use the VGA connection for that purpose, I bought a DVI-D cable. I have connected it properly, and used CRU to add a 1680x1050@50Hz display mode.
When I choose that, the monitor does change the mode, and although shows a "input signal out of range", it initially seems to display the mode just fine. Doing the online test at testufo.com it appears to show the 50 FPS synced to 50Hz just fine, no drops it seems. However, I'm experiencing two anomalies detailed below.

Anomaly 1
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I experience random pixels distributed horizontally along a horizontal border separating backgrounds in different colors. Say there is a horizontal border separating a "background" of white and another in some other color. Along both sides of that border, a few scanlines off-set from the border and possibly each consisting of a few scanlines (at least one), there are scanlines of random pixels distributed and redistributed each frame (or each few frames), that seems to have the same color of the background on the other side of that border. Although I'm not an electronics guy, I suspect that may have nothing to do with cable/bandwidth since I'm underclocking (and not overclocking) the refresh rate. So I'm curious what can be causing this, and if there may be a solution.

Anomaly 2
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This may possibly not have anything to do with the display and rather a fault of the amiga emulator, but I suspect not entirely so. The most obvious experience I have of this one is when I run some physics implementing game like say, Pinball Dreams. The ball often goes nuts with absurd and very physics-law-breaking behavior. Particularly when the left flipper is involved. It is as if the ball is "induced" with some spin out of nowhere driving the ball usually too far right, and sometimes it just bounces back and up. Very bizarre, and I cannot experience that when running 60Hz, whether with vsync turned on or not in the emulator. And yes, most of the amiga games where written for PAL systems (50Hz).


EDIT
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Btw, Here's my system.

CPU: AMD Athlon X2 5200+
OS: Win7 32bit home premium
GPU: Radeon HD4550 AIO
Catalyst: 13.9