adding memory causes memtest+ to fail

[bwanaaa]

current setup
asus p5k wifi deluxe mobo
CQ6600
4 sticks of 1 gig ram - G.SKILL F2-6400CL4D-2GBHK 4-4-3-5

this setup is memtest+ stable and the ram speed in memtest+ is 5024 mb/s
mobo set at 400x9, Vcore 1.425, Vmem 2.1

I removed the Gskills and put in 2 of these 2 gig sticks - Patriot
PDC24G6400LLK running at Vmem 2.2v 4-4-4-12
Memtest+ runs fine with a reported speed of 5209 mb/s

When i try the patriots with the GSKILLS,
(making sure the patriots and gskills use staggered memory slots
so each memory brand is on the same channel)
I get a reported speed of 3005 mb/s and failures on test 6.
(Vmem has to be 2.2v because the patriots alone will fail test 6 if
vmem<2.2v) 4-4-4-12 as well as 4-4-4-15 fail. no other timings tried.

Why the lower speed? Why the failures when each brand alone is ok?

 

[wpshooter]

I would not mix memory, brand or otherwise.

 

[The-Noid]

you will most likely need to increase nb voltage when going with 4x 1gb dimms.

 

[brencat]

Hi bwanaaa. Verify that the 2 x 2gb Patriot sticks are in the first channel and the 2 x 1gb GSkills are in the 2nd channel. Remembering my DDR1 days, you always want to make sure the larger quantity of memory is first.

Assuming you've already checked that, look in your bios for a line item called Transaction Booster. Try setting it to Disabled as opposed to leaving it on Auto/Enabled.

Re-run memtest. If it fails again, raise NB voltage 2 notches and retest.

If it still fails, loosen timings to 5-5-5-15 and see if you can pass memtest.

Some P5Ks have issues with all 4 RAM slots populated. The larger 2gb Patriot sticks are likely causing the problem since 4 slots with the smaller 1gb G-Skills apparently work fine.

 

[bwanaaa]

tnx all. wilco.