Are the chips on these memory cards the same?

[b1g bleu]

F3-12800CL9D-8GBRL (2X4gb kit)
F3-12800CL9S-4GBRL (1X4gb)

I'm assuming the S is for single card and D for dual?

[GSKILL TECH]

Yes, the 4GB is guaranteed for single operation (4GB), where are the 8GB kit is guaranteed for dual channel operation.

Thank you
GSKILL TECH

[b1g bleu]

so I can mix two singles with the dual set I have?

[Tradesman]

Generally you can get them to work together, some just pop right in and go, then again at times you'll get sticks that won't play well together. It's always best to get the full amount you want in a single set. If you already have them, give it a shot and if any problem get back to us, we can generally adjust the voltage for them to play together

[b1g bleu]

OK, got the new 8gb set and have been trying to get them to run with the 2x4gb singles @ 1600 but pc won't last more than 13 minutes before crashing on memtest 4.20. set Bios defaults and pc has been running ram@1333 since last night. I saw sticky about OC'ing the cpu but I'd just rather have the ram work together @ 1600. I noticed when I tried the ram at 1600 the voltage was at like 1.64 instead of the 1.5v it's at now.

ASUS M4A89GTD-PRO/USB3 BIOS 1703 ALL DEFAULT SETTINGS
AMD PHENOM II 1075T 3ghZ
1 x F3-12800CL9D-8GBRL (2X4gb kit) NEW
2 x F3-12800CL9S-4GBRL (1X4gb) ORIG.
XFX AMD RADEON HD 6870 BLACK EDITION 1GB DDR5 PCI-E 2.1X16 ALL DEFAULT SETTINGS
CORSAIR TX750W POWER SUPPLY
WINDOWS 7 HOME PREMIUM 64BIT

[b1g bleu]

Did I get the wrong ram?

I just checked the ram configuator on the gskill site and my mb shows 1.65v ram, model
[FLS] F3-14400CL9D-4GBFLS (2Gx2). Using these chips would only yield 8GB, and they're still not a matching set of 4.