I have (3x) 2GB 1600 MHz Corsair full DIMMs - TR3X6G1600C8D. They've been on the shelf for years. Will send them to you for free. Just PM me your snail-mail address. They aren't 4GB though, sorry.
The only issue would be that all the modules would probably run at 800 mHz as it's normal for RAM to run at the speed of the slowest component.I really want 16gm of RAM but maybe some faster RAM would at least help for a while... Would you think there would be any issues mixing 3 1600mhz modules with one 800mhz module?
The only issue would be that all the modules would probably run at 800 mHz as it's normal for RAM to run at the speed of the slowest component.
You'd be better off running the 3 1600mHz modules without the 800 mHz module in the mix and have 6 GB.
Are you sure you actually have DDR3? 800 MHz DDR3 is extremely uncommon, usually only used in OEM machines. Most MFGs started at 1066 or 1333 for DDR3.
The actual speed on PC3-10666 modules (1333) is 666 MHz. If somewhere it said 800 MHz, you'd have PC3-12800 (1600) modules.
You might want to look at the label on the sticks themselves to verify, because applications like CPU-Z will only tell you what they're currently running at, and sometimes the SPD data.
Serial Presence Detect (SPD) tables are stored in a tiny ROM on the memory module which gives the various timings/clock rates supported.
Not all manufacturers implement SPD correctly, many often just enter one set of values and leave the rest of the table blank, or fill the extra space with nonsense. But just because timings/clock rates are listed in the SPD table, doesn't mean the memory is running at that speed. The speed its currently running at is listed under "DRAM Frequency" on the Memory tab, which in your case is 836 MHz, so this means that you likely have 1600 MHz DDR3 which is slightly overclocked.