Can I combine two different frequency and size memory modules?

Question

I currently have a EVGA p55 le motherboard. I had installed 2x2gig and 1x1gig OCZ memory sticks with the 2x2 gigs in the zero and second slots and the 1x1gig in the first. I recently installed a second 1x1gig in the last slot. I started the PC and windows booted just fine, but when I started to open applications, the system froze and rebooted. I then placed the 2x2gigs in the zero and third slots and the 2x1gigs in the first and second slots. Same issue. I have also tried just installing the single 1x1gig stick with the 2x2gigs and the system boots and operates just fine, no matter which stick is used.

What's funny is that I can use explorer (accessing the hard drives) but the minute I start chrome or something else, then it shuts down. Does it matter which slot I place the memory sticks in? Also the 2x2gigs are 1066 speeds and the 2x1gigs are 1333 speeds. Does that matter? and does the fact that they are different sizes matter?

I'm still running the MemTest86+ but it has come up with an error the specifics are:

Tst | Pass | Failing Address | Good | Bad | Err-Bits | Count Chan

8 | 0 | 0016fe58418 - 5886.3MB | 542f429c | 542f4263 | 000000ff | 1

What exactly does this mean, and how should I approach?

Also my bios revision is A70, i understand that A59 had issues.

Answer 1

This is roughly the bottomline,

1. You need to use the same size memory on the two slots forming a DDR2 bank.
2. You will need to 'match' the DDR2 slots to get the DDR2 advantage,
   else, that memory will not perform -- but, it will not fail the way you describe.

Have you checked that all your memory sticks are fine and your memory slots are clean?

If your slots are not clean, a memtest could pass once and then fail other times, also moving the memory after the test could again show failures (after the memtest passed in earlier positions).

If you have failing memory in some specific areas, starting more applications can make the OS reach these areas and 'trip' the system by a memory-access failure. This could be the case you describe. However, if you run a full memtest without moving the memory it should detect these failures.

If re-runs of memtest show different locations of failure or inconsistently pass/fail on repeat runs with or without replacing memory across slots, you very likely have a bad, damaged or unclean slot.

Update: A review of the memory support of your EVGA P55 LE motherboard.

Memory: Four DDR3-DIMM sockets
(up to 16 GB up to DDR3-1333/PC3-10600 officially or up to DDR3-2000 non-officially).

_{This may be slightly off-topic but probably of interest.}
So, your board also supports DDR3 in dual-channel (rather than tri-channel) mode.
For all practical purposes of slot arrangements, you are working on DDR2 theory.
This short treatise on tri-channel memory should help.

---

Update on your memtest data:
The Memtest86 tech support page describes your errors.

Tst: Test Number
Failing Address: Failing memory address
Good: Expected data pattern
Bad: Failing data pattern
Err-Bits: Exclusive or of good and bad data (this shows the position of the failing bit(s))
Count: Number of consecutive errors with the same address and failing bits

Interpreting your error line,

I have split your error output into two parts here,

  Tst , Pass , Failing Address        ,
  8   ,  0   , 0016fe58418 - 5886.3MB ,

^{Your problem address is beyond 4GB.}

  Good     , Bad      , Err-Bits , Count Chan 
  542f429c , 542f4263 , 000000ff , 1
#       ^^ !=      ^^ ;       ^^ Mask indicating error area.    

^{You problem data is shown above.}

Things you can re-check,

1. Does a re-run produce same errors?
2. If you re-position your memory over the available slots, do the errors change?
   (You can switch the sticks across slots of the same bank for example)