I've had the countdown crash myself. You could probably calibrate a stopwatch with it. In my case it was something closer to 60 minutes and then it dropped to 20 minutes when I significantly increased the mod load. When I decided to hunt for the bug more actively, I doubled the amount of high-processing demand mods I was loading and that made program terminate right on 37 seconds every time. I eventually found that adjusting some ini settings made a big difference:
You might want to adjust your SKSE.ini settings. It's in:
C:\Program Files (x86)\Steam\SteamApps\common\Skyrim\Data\SKSE\SKSE.ini
The settings I currently use for an 8gb Athlon 6000 system (Windows Vista Ultimate x64 with all the extra bugs) with 4gb set aside for the video card (which has 2gb of its own) are as follows:
Also, I reserve a second hard disc for swap file operations. It cuts down on fragmentation of the main hard disc and speeds things up by giving swap file operations and regular disc operations their own separate trio of drive heads (seeing as I won't be using SSD drives until the manufacturers stop selling those rejects which deteriorate with use, more so, than a mechanical hard disc).
Also, Skyrim.ini settings, under:
...\My Games\Skyrim\Skyrim.ini
In my case, I use:
The key settings, here, are in "Golden Rod" colour. Other than the relationships shown byhttp://www.gamesas.com/user/728772-dhjudas/ (http://www.gamesas.com/topic/1274926-ugridstoload-skyrimini-comparisons-and-explanation-default-57911/), I don't know what relationships or dependencies there are between these variables. In my own setting, I've assumed significant binary patterns in relationships and that everything has to fit one of my 4096mb blocks. This assumption concerning totals not exceeding maximum available memory solved a problem I was having where iMaxAllocatedMemoryBytes was reverting to a negative number in-game.
In any case, if you're using the standard 5uGrids the numbers I'd roll with would be more along the lines of:
SKSE.ini:
and Skyrim.ini:
I have no idea what dictates optimums for min and max page sizes - but I have verified that adjusting iMaxAllocatedBytes requires checking the value in the console in-game to verify that it's working properly and hasn't reverted to a negative number due to excessive setting and I'm inclined to scale these numbers to preserve a rough working set of proportions.
I hope this can be useful and good luck with getting your new system working properly.