New Rules for RAM??

In most cases, memory should be in pairs for best performance, but it's not an absolute requirement.  However, I'm surprised that the OEM Dell wasn't two 1GB modules.

See THIS from Crucial Memory (Crucial memory is guaranteed to work in Dell's).

Systems that do Dual Channel or Tri Channel Ram can use Odd amounts.

Most Dual Channel Dells WILL work with 1 or 2 but not 3 and with 4 ram sticks.

AKA it goes into dual channel mode when there is a pair involved and sticks with PAIRS required after that.

However the system is designed to work in single channel mode to test ram sticks 1 at a time.

I also do not recommend mixing speeds and vendors for ram. 

Tri Channel boards can have 3 slots or 6 slots and can use odd numbers like 3.

I see the I7 designs using triple-channel memory mode.

Recommended Memory Configuration

While installing or replacing memory, refer to the table below. For the location of the memory-module connectors, see System Board Components.

 

Model	One module	Two modules	Three modules	Four modules
560	DIMM1	DIMM1 DIMM3	DIMM1 DIMM3 DIMM2	DIMM1 DIMM3 DIMM2 DIMM4
570	DIMM4	DIMM4 DIMM3	DIMM4 DIMM3 DIMM2	DIMM4 DIMM3 DIMM2 DIMM1

 

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Setting Up Dual-Channel Memory Configuration

Inspiron 560

 

 

 

1

Pair A: matched pair of memory modules in connectors DIMM1 and DIMM3

2

Pair B: matched pair of memory modules in connectors DIMM2 and DIMM4

 

Inspiron 570

 

 

 

1

Pair B: matched pair of memory modules in connectors DIMM2 and DIMM1

2

Pair A: matched pair of memory modules in connectors DIMM4 and DIMM3

The 570 has 4 memory slots and your service manual online has the correct placement. One memory chip should have come in slot 4 and if you add one more it would go into slot 3. You should look at the manual HERE <ADMIN NOTE: Broken link has been removed from this post by Dell>

PS Make sure you look at the 570 info and not the 560--the memory slots are different.