DDR2 - "x4" versus "x8", AMD versus Intel

[VirtualLarry]

(This was originally posted as a reply in FS/FT, but I thought that the discussion belonged here.)

I don't get it. OP asked for Core2Quad CPU, didn't he? That RAM you linked from ebay, is "for AMD only".

I've bought some of those cheap 4GB DDR2 DIMMs, and they didn't work in an Intel "Q" chipset S775 board.

My understanding is that those newer, cheaper, "high-density" / "AMD only" DIMMs only work in AM2 / AM2+ rigs.

If there are cheap DDR2 4GB DIMMs / kits that work with Intel P35 or G41 boards, please let me know!

Edit: Well, I decided to pull one of my Core2Quad Q9300 rigs out, and swap in some of those (branded) Chinese DDR2-800 4GB sticks. (Hynix)

They had a very similar label to the ones I already had in there, which was re-assuring. Amazing, after swapping in one of the 4GB DIMMs, it booted! But my joy was short-lived, as Windows 10's Control Panel, System, showed "4.00GB (2.00 GB accessable)", or something along those lines.

In short, Windows can detect the total size of the DIMM, through the SPD info for that slot, but the system chipset can't access the full size of the DIMM.

if the rig you put those DIMMs in, has an Intel chipset, and isn't running Windows, you may never have noticed that you only have half of the RAM accessable that you've installed.

Regardless, kind of irresponsible to suggest buying cheap "AMD only" high-density DDR2 4GB sticks from China, for someone asking about a Core2Quad CPU (which necessarily runs on an Intel chipset).

Edit: Wait, it gets more complicated. My branded Hynix 4GB DDR2 sticks are "2Rx8". The picture (zoomed in) of the RAM in that ebay listing is "2Rx4".

I also have some unbranded 4GB Chinese DDR2.

I now believe that the "2Rx4" is "high-density" (AMD only), and the "2Rx8" is "low-density". Which is why I was even able to boot my branded 4GB sticks in my P35 board, whereas my unbranded 4GB DDR2 sticks wouldn't boot in an ITX Intel board.

So, my prediction is that these Hynix-branded "2Rx8" sticks should work in my P45 S775 board, giving me 4x4GB, or 16GB RAM.

I'll build that rig soon, so I can test that theory.

 

[Oyeve]

Dont worry. I sold him some HQ 2x8gb sticks of Mushkin. I had them running fine in a P35 mobo with a Q9500 in it,

 

[VirtualLarry]

I was more interesting in finding out if my theory was correct, that DDR2 DIMMs labeled with "2Rx8" would work with Intel chipsets, even if they couldn't utilize the full capacity of the DIMM (With my P35 board), but it was the "2Rx4" DIMMs that were in fact "AMD-only" and "high-density".

IOW, I ordered "AMD only" RAM, and I in fact received branded Hynix sticks that were "2Rx8", which means that they are actually low-density, and should in fact work with a Gigabyte P45 DDR2 board, to give me 16GB of RAM. Which, I'll test hopefully soon, as soon as I dig out my ATX case under some boxes, and get the motivation to build an old Core2Quad rig.