Motherboard boots with only one memory module, starts "weak" with two

[zartom]

First post. let's try... No help at Tom's

New simple build, everything was bought used. Last owner says he used it with two with no problems but i only have his word for it. Motherboard has two slots only, and both modules, plus another corsair for testing, all works good in slot 1 each on their own. All of them are 4GB DDR3 1600.

Here is the weird part: when both modules are installed, the motherboard fires up slowly and weak. what do i mean? All fans and and drives start spinning much slower than normal. sometime they even turn off for a second before starting up again all the way to POST.

There is always one good POST beep. Everytime it reaches the "checking memory" line at POST listing the correct current size (8\4GB). the difference is that with one installed it goes to check drives and with two it hangs and go into a boot loop.

I've tried disconnecting everything (USB and front panels connectors included) and starting only with PSU and onboard GPU connected.

any more ideas? i see this problem is common on the forums but with slights variants

Motherboard: Gigabyte H61M-d2-b3 (rev. 1.0)
CPU: i3 2130
Memory: some unknown one (having troubles identifying), but also with a corsair vengeance
PSU: chieftec aps-550s

thanks in advance!

[Tiger]

Memory manufacturers do not recommend mixing memory kits, regardless of brand or model.

By mixing memory kits together, there may be compatibility issues such as unable to boot or unable to operate at rated specifications.

Each memory kit is thoroughly tested to ensure compatibility within each memory kit. Because the memory manufacturer has not tested your new memory with your old memory, they cannot guarantee compatibility when multiple kits are used or when single module kits are combined.
 

[zartom]

Thank for the reply, but i guess i didn't explain my self well. i'm sorry.
I have a matching pair of 4GB each, so total is 8GB DDR3 from this brand (Ramaxel maybe?)
I've only mentioned the Corsairs to emphasize that it is not a faulty module.

[zartom]

any chance to reopen this question? still the same here

[absic]

Have you tried manually setting the timings & speed in BIOS?

Technically your CPU only supports modules rated at 1066 or 1333 Mhz so I would try setting the speed at one of these, using the rated timings for your modules.