7900GT memory overclocking issues

I have a Gainward 7900GT with stock speeds of 550/1400. The ram is rated at 1.4ns, so the margin for overclocking it is small.

I have managed to hit 765 in the core, and its rock solid stable after 8 hrs of 3dmark06. (pencil vmod and watercooled.)

The memory wont shift past 1420 though, which is severely limiting me now.

If I were to increase all the memory latencies in the bios with nBiToR by say, 30%, would that translate to a ~30% clock speed increase on the RAM in a similar way to overclocking main system memory?

The latencies would be the same or similar in terms of time, although bigger in terms of clock cycles, but the memory bandwidth should be higher, correct?

The RAM is Samsung K4J55323QG-BC14, Rated at 700mhz according to the samsung site, and 1.8v +- 0.1v. Its running at 2.08v stock so it doesnt look like its going any higher

Are they using the same Samsung ram?

Having read Here, it seems the latest EVGA 7900GT KO SC cards, which run at 580/1580 at factory settings, use the EXACT same RAM as my card.

This would seem to indicate I should be able to squeeze at least 790(1580) out of my RAM.

nBiTor seems to indicate that the timingset 7 on the EVGA 7900GT KO SC Bios on mvktech.net are even tighter than my timings.

The EVGA card uses 2.0v, and my RAM voltage measures at 2.08v. I have taken it up slightly to 2.28, and gained no increase in overclocking headroom at all.

I even tried Flashing my card with the EVGA BIOS, but, I assume because of the different board design of my card, I simply ended up with a garbled screen (reflashed with old BIOS with the aid of a PCI card)

Anybody have any clue why?