Memory upgrade slowed memory speed - PO3-600

Bubba_Fett

I've got a PO3-600 that came with 16 gigs of ddr4 at 2666. (2* 8 gig sticks)
I bought another pair of 8 gig sticks also rated for 2666 mhz but when I installed them the memory speed of all of them seems to have dropped to 2128 mhz according to my 3Dmark test. Before the new sticks were installed, 3Dmark was showing it at 2660mhz. The new memory is Corsair Vengance lpx 2666.

Before installing the new memory I looked in the bios, but didn't see anything about memory timing or any other memory settings. The bios looks very basic with few options to set and is american megatrends dated 05/16/2018. I haven't even bothered looking for an upgrade for it since this is the first issue I've had with this machine since buying it.

Any clue how to get my memory speeds back up to what they were while still using the new memory I bought?

billsey

Does yours have an 8th gen or 9th gen CPU? They made motherboard changes between them.

Bubba_Fett

It's an I7-8700. I presume that's 8th gen?

StevenGen

Bubba_Fett said:

I've got a PO3-600 that came with 16 gigs of ddr4 at 2666. (2* 8 gig sticks)
I bought another pair of 8 gig sticks also rated for 2666 mhz but when I installed them the memory speed of all of them seems to have dropped to 2128 mhz according to my 3Dmark test. Before the new sticks were installed, 3Dmark was showing it at 2660mhz. The new memory is Corsair Vengance lpx 2666.

Before installing the new memory I looked in the bios, but didn't see anything about memory timing or any other memory settings. The bios looks very basic with few options to set and is american megatrends dated 05/16/2018. I haven't even bothered looking for an upgrade for it since this is the first issue I've had with this machine since buying it.

Any clue how to get my memory speeds back up to what they were while still using the new memory I bought?

Have a look at your OEM 16GB 2x8GB DDR4 SDRAM exact timings (from the manufacturer) of your ram with GPUz or 3Dmark. Try to match those timing’s exactly, as and when mixing ram the ram always works at the lowest common denominating speed as that is probably what happened in your case, either the OEM ram timing’s are slower or the Corsair Vengance LPX 2666MHz is (which I don’t think that the Vengance LPX is) as a lower timing gives you a lower reading from 2660MHz and you are getting 2128MHz by mixing all these different DDR4 SDRAM rams together. If you want the 2666MHz speed have the same ram from the same manufacturer, replace the OEM ram with 4x DDR4 SDRAM Corsair Vengance LPX 2666MHz then you won't have any problems. 

billsey

Yup, the i7-8700 is an 8th gen. Your system supports 2400 and 2666 memory, up to 16GB per slot, so 64GB in total at max. I don't see anything obvious as to why the speeds drop to the lower standard with the Corsair memory installed. Perhaps something to do with its overclocking support?

Bubba_Fett

Thanks for the advice guys. I'm thinking I'm going to have to buy another 16 gigs of the corsair memory so that all 4 sticks are matched. The annoying thing about all this is that I could have bought a pair of 16 gig sticks for $35 more (was $94 cdn for a pair of Corsair 8's) but didn't as I was told that Win 10 home edition doesn't support more than 32 gigs of memory. If I had I could have just pulled the OEM 16 gigs out and not had to worry about them being compatable. 

Anyways, I'll try pulling the OEM sticks out and see if I'm getting 2666 with just the corsairs, and if I am, get another pair of the same. (and I'm aware that the Corsair sticks will have to go in the slots that the OEM were in for the test)

Since there's nothing in the bios to adjust memory timing, is there any way to get around that with external apps? 

StevenGen

Bubba_Fett said:

Thanks for the advice guys. I'm thinking I'm going to have to buy another 16 gigs of the corsair memory so that all 4 sticks are matched. The annoying thing about all this is that I could have bought a pair of 16 gig sticks for $35 more (was $94 cdn for a pair of Corsair 8's) but didn't as I was told that Win 10 home edition doesn't support more than 32 gigs of memory. If I had I could have just pulled the OEM 16 gigs out and not had to worry about them being compatable. 

Anyways, I'll try pulling the OEM sticks out and see if I'm getting 2666 with just the corsairs, and if I am, get another pair of the same. (and I'm aware that the Corsair sticks will have to go in the slots that the OEM were in for the test)

Since there's nothing in the bios to adjust memory timing, is there any way to get around that with external apps? 

To find out the exact MAX RAM of your PO3-600 go to cmd prompt and use it as administrator and use this command: 

wmic memphysical get MaxCapacity, MemoryDevices

In the example above its for an Aspire V3-571G that has 2x physical RAM slots but the specd mainboard is also used for a desktop hence the figure 4 for MemoryDevices above so, the cmd RAM total is 33554432 divide by 1048576 = 32 divide by 4 = 8GB which is the MAX RAM divide by 2 actual and physical slots = 4GB per slot that signifies the MAX RAM per slot, simple. 

You never ever mix different timing RAM as the RAM will always work at the lowes timings/speed and that is what’s happened to you, all RAM has to be the same preferably, manufacturer and spec e.g. DDR4-2666MHz and the same timings not mixed up DDR4-2666MHz timings with or other DDR4-2400 of different timings, simple.  

billsey

Yep, Windows 10 Home is limited on how much memory it will support... The 64bit version will only allow 128GB of system memory, instead of the 2TB Pro supports.