2 different 8GB sets. Can I run them at the same speed?

[Denic]

In my PC I have 2 different 8GB sets.

2 X 4GB - Kingston KHX1600C9D3/4GX http://www.kingston.com/datasheets/KHX1600C9D3_4G.pdf

2 X 4GB - Corsair CMZ8GX3M2A1600C9
http://www.corsair.com/en-gb/vengean...z8gx3m2a1600c9

Only one of the sets is running at 1600MHz and that's the kingston set. The other set is running at 1333Mhz.

Can I get both sets running at 1600Mhz?

[KeyboardDemon]

I was running two 8gb kits in my PC, both were Corsair Vengeance 1866 kits, the same part number on the packaging but they would not run together though both kits run fine on their own. I think you would end up with the same stability issues I was experiencing.

[Denic]

Well they seem to run together fine just not at the same speed.....

[aidanjt]

Only one of the sets is running at 1600MHz and that's the kingston set. The other set is running at 1333Mhz.

Can I get both sets running at 1600Mhz?

According to the specifications, sure. Be careful with the timings though, the Kingston set has a CAS Latency of 11, vs the Corsair's 9, so if you set them to 9 you'd technically be overclocking the Kingstons and that'd require some testing to ensure stability.

[Denic]

According to the specifications, sure. Be careful with the timings though, the Kingston set has a CAS Latency of 11, vs the Corsair's 9, so if you set them to 9 you'd technically be overclocking the Kingstons and that'd require some testing to ensure stability.

But the issue I'm having is that one kit is running at 1333Mhz and the other at 16000Mhz. I want them both running at 1600Mhz. How can I do this

[kalniel]

If both kits are rated at 1600 for the same timings and voltages then you should be able to run them both at 1600. Just set them to 1600.

Looking at the spec sheets they're rated for different timings at the same voltage, which isn't ideal, so you'll have to either run both sets at 1.65V cas9 1600mhz, or both at 1.5V cas11 1600mhz. You may get away with running them at different voltages but it's easiest to keep everything the same between them.

[Denic]

If both kits are rated at 1600 for the same timings and voltages then you should be able to run them both at 1600. Just set them to 1600.

Looking at the spec sheets they're rated for different timings at the same voltage, which isn't ideal, so you'll have to either run both sets at 1.65V cas9 1600mhz, or both at 1.5V cas11 1600mhz. You may get away with running them at different voltages but it's easiest to keep everything the same between them.

In my bios I don't see settings for all 4 sticks I just see ram frequency setting etc. I set it to 1600MHz but as I say only 1 kit works as 1600Mhz and the other stays at 1333Mhz

[GoNz0]

it will run at the slower speed, best bets to leave it at stock setting as an XMP profile may cause stability issues.


the new DDR4 X99 chipsets do not play well at all with mixed ram, even 2 packs of identical ram will cause issues.

[kalniel]

In my bios I don't see settings for all 4 sticks I just see ram frequency setting etc. I set it to 1600MHz but as I say only 1 kit works as 1600Mhz and the other stays at 1333Mhz

At what timings and voltage?

[EndlessWaves]

In my bios I don't see settings for all 4 sticks I just see ram frequency setting etc. I set it to 1600MHz but as I say only 1 kit works as 1600Mhz and the other stays at 1333Mhz

I didn't think that was possible. What's reporting those speeds to you?

[Ttaskmaster]

I was running two 8gb kits in my PC, both were Corsair Vengeance 1866 kits, the same part number on the packaging but they would not run together though both kits run fine on their own. I think you would end up with the same stability issues I was experiencing.

What, the exact same RAM, same specs and everything?

Can I ask what the problem was?
I'm a bit concerned, as I have 2 x 4GB 1866 9-9-9-24 and have just ordered a second lot of this exact same RAM... I thought I could just slot the second lot into my other channel and be good to go?

[watercooled]

I was running two 8gb kits in my PC, both were Corsair Vengeance 1866 kits, the same part number on the packaging but they would not run together though both kits run fine on their own. I think you would end up with the same stability issues I was experiencing.

It sounds like that could be a memory controller/load issue - adding more DIMMs to a channel increases electrical loading, decreasing stable clocks. That's why servers/workstations use registered memory. It's not all that common for it to happen with two channels but it's not unheard of, especially with higher clocks/tighter timings on XMP profiles. Because there's no real reason two separate kits shouldn't work together on a system.

[GoNz0]

if you double up do not use XMP profiles if you have stability issues, if they work at stock RAM speeds then that is the price you pay for buying 2 kits over the (quite often) premium you pay for the bigger matched kit.

If it is really bad buy the bigger kit, return the new set you bought and flog the old kit on Hexus.

[KeyboardDemon]

@watercooled: @GoNz0: Does that mean that if I put the other set of RAM back in my system and set them up with manual settings to all run at the same speeds with the same timings etc... then I should no longer see those issues?

I can't return the more recently acquired RAM, I had been using it in another rig for 6 months before transferring it to this rig.

[watercooled]

Well you can't choose separate speeds for each DIMM anyway - by default they'll run at the highest commonly supported speed of the modules installed. However it may be causing issues if the motherboard is picking an XMP speed by default. Sometimes that will work, sometimes not.

Unless something is faulty (e.g. a DIMM slot), all 4 DIMMs should run simultaneously but you may have to pick a lower clock speed/looser timings.

[kalniel]

@watercooled: @GoNz0: Does that mean that if I put the other set of RAM back in my system and set them up with manual settings to all run at the same speeds with the same timings etc... then I should no longer see those issues?

I can't return the more recently acquired RAM, I had been using it in another rig for 6 months before transferring it to this rig.

Indeed - manual timings will help, but you may also need to lower the speeds and/or raise voltages either on the DIMM or the memory controller - working four DIMMs is just more work than two so things need to be relaxed a bit and if anything was near the limit of stability the extra work might just push it over.