GTX 580 Twin Frozr II O/C - confused by bios version number, and how to flash

Question

Hi, my first post here. But I've been reading a bit here. Still, I get confused by this whole vga bios thing, version numbers and how to flash... Ok, so here's my situation:
I have two PC's. Both with one MSI Twin Frozr II O/C GTX 580 card inside. It seems to me that both are working according to specifications, GPU-Z reports:
GPU clock 800 Mhz, Memory 1024 Mhz, Shader 1600 Mhz for the borth of them.
Now, one of them seems not to be totally stable (this is the newest I bought a few days ago). It locks up/crashes in some games. The other seems ok, I've been having that one for a while. Could this be a GPU core voltage problem? GPU-Z reports for the both of them:
VDDC 0.955 v
I've tried running MSI afterburner, changing core voltage to 1025, and in afterburner settings enable "Force constant voltage". Still, GPU-Z, which I keep running at the same time, still reports only 0.955. I thought this setting in Afterburner would change voltage to 1.025?  This situation is for both the old one and the new one.
Now to the Bios "problem".
The newest card (the not so stable one) reports through GPU-Z: Bios Version 70.10.20.00.01
The oldest (stable) card: Bios Version 70.10.17.00.01
So... which one has the newest bios? Seems to me it is the newest card.
BUT - when running MSI Live Update 5 (newest version) it says for both the cards that they have the the newest bios version, and there's no need to upgrade??
SO - I go to the MSI webpage: http://no.msi.com/product/vga/N580GTX-Twin-Frozr-II-OC.html#?div=BIOS  to download the newest bios manually, just in case.. But there it gets more confusing. The Bios version found there is :NV255MS.104(.zip).
And also, on that page I can not find how to use that file. Extracting it just gives me the file NV255MS.104    and no extension.
So, which bios is the newest one? 70.10.20.00.01  (the highest number, in the new card, but not stable in some games), 70.10.17.00.01 (in my old card, but seems stable in the games I've tried), or NV255.104  (which I don't know how to use).
I've flashed my main board bios many times over the years in various set ups, the bios on two different SSD disks and so on.. never had a problem with that, or finding out if I have the correct bios, how to do it and so on.
Maybe I'm stupid, but this MSI Twin Frozr II O/C GTX 580 bios thing confuses me a lot... So, how do I solve this situation?   

Answer 1

I am also interested in the answer as I have 2 MSI N580GTX-M2D15D5/OC cards. I can find the latest BIOS file "NV801MS.KG4.zip" and know the version is "KG4". But how do you relate this to the current BIOS version Afterburner or GPU-Z provides? The version they each provide is "70.10.17.00.01" for both cards. The only other way to determine if they are up to date is to install and run MSI Live Update. MSI Live Update responds that they are up to date with no current version or online version information on the Live Update tab. At least the information on the Home tab states the same VGA BIOS version as GPU-Z and Afterburner. I can can only assume that the BIOS is updated by using MSI Live Update.
Also just for the additional information GPU-Z displays my VDDC as 1.039 briefly then 0.995 constantly when switching between cards. I actually have the cards set to 1.050 with Afterburner to be stable when running Crysis 2 DX11 updates.