Problem with having 4 GB memory

step #1; Memtest86+ - Advanced Memory Diagnostic Tool
run all day/night. if pass; set voltage to 1.9 --if you haven't already

if still bluescreening with both in, drop the speed to 667
if still no, loosen the timings --some crappy boards can't drive the ram the way they need to be-- to say, 5-6-6-15 or maybe even 18

w7, being beta still, is a touch more sensitive to the little quirks of hardware configs, as such it tends to harf on the slightest little thing xp (now into sp3) will overlook and ignore.

then again, i've never been a biostar fan myself.

on a side note as well; motherboard makers don't make the bioses, they get a single base set from whatever chip makers they have in the board --ie; intel for chipset, realtek add-in from realtek (for audio and lan, etc)-- and then combine them into a single file they flash after making sure it at least mostly works. the main chunk of code however, still comes from the chip makers.

asus, msi, and gigabyte all do inhouse board manufacturing, and i think asus might do code from the ground up, unsure

evga just sources everything from nvidia and foxconn and rebadges with their logos and manufacturer strings, while editing the code in the bios files to provide bugfixes if needed/warranted

dfi is mostly foxconn

ecs is complete trash. fun fact 80+% of all ecs boards get returned and stuck back out on the shelves for the next noob.

everyone else? no idea, but try the tips at the top of the list and if nothing, then i'm out of ideas. :/

Abit used to have a good board out while they were no match for Asus, Gigabyte, and MSI there. While Biostar isn't at the bottom of the list it seems their support is!

The personal chioce still seen here for chipsets is NVidia while I may be looking AMD for the next build on that.

Another thing besides adjusting the dram timings and memory clock would be looking at lowering the voltages like 1.8-1.95v for seeing cooler memory temps to start with. If they say 2-2.5v lower it down to 2v.

My friend had a biostar board, whilst he did not have the same prob as you mate, he found the lack of support unreal. However, i would agree with the poster above that it may be memory timings. Usually lower end boards cannot handle the ram correctly. As a result 'various' things can happen. I always found that when purchasing a system i spend just as much on a board as i do the CPU. I remeber that on certain gigabyte boards you could access a hidden menu in bios ( ctrl+1, if i remember right) this allowed the user to change ram voltages etc... Is there nothing like that for your board? Im just hazzording guesses here. But it does sound the board is the culprit here if you have good ram

The feeling I get from all this with the slower timings is that the board is geared for standard but not performance type memory to start with. This is why when going to pick out a board browse around a bit to see what brands and types are on the recommended list if the manfacturer has one. That shows what has been tested and works.

If the memory is rated at 1.8v or 1.9v to 2.2v you wouldn't want to be going over 2v to start with! With everything set to auto and still not seeing both dimms working together a close look at the typical memory recommend would be a start while the type of memory as well as voltage requirements are going to keep coming up.

Timings and voltages will see an immediate effect if there's any type of mismatch between dimms as well as what the board actually takes. You mentioned slowing the timings down to 5-5-5-12 but what is the normal default for the memory itself? 4-4-4-12? something around there?

Something is off with the second dimm since all this started when adding that in suggesting a possible mislabeled if not defective dimm. I think the type is the most likely problem however if both dimms have been tested individually and work on their own but not together. The board uses value or standard ram while you bought performance memory leading to problems for that model board.