PDA

View Full Version : Memory for Skylake build



BrotherDragon
26-07-2015, 02:36 PM
Getting ready to build a new computer in September when Skylake(i5-6500) comes out. First, what I've seen says that Skylake will support DDR3L(!)-1600 and DDR4-2133 memory. At first I thought it was a no brainer, get the DDR4 but aside from being more expensive it seems that DDR4 is currently not any faster than DDR3 due to higher latency and timings. So I start looking at DDR3L kits and find that almost all are for laptops. Most of the kits that are for desktops are 4x4 quad channel and I found only one by Mushkin that was 2x8 dual channel. I'll definitely start with DDR3 memory with plans to upgrade to DDR4 when latencies and timings improve. My questions are whether Mushkin is a decent brand, are there other brand name kits out there I should look at and will I have to wait until the i5-6500 comes out to know if it will support quad channel or if I'll have to stick with dual channel kits?
______________________________
"I'm trying to think but nothin' happens" -Jerome "Curly" Howard

dugimodo
26-07-2015, 03:19 PM
Very unlikely any of the mainstream parts will be quad channel. That's more enthusiast and enterprise class which will not be arriving this year for skylake. Personally I would not buy any RAM before the Motherboards and CPU are actually available otherwise you are making assumptions that may prove wrong or may limit your motherboard choices. Also what could happen as DDR4 becomes the new standard is prices will start to drop, buying now or immediately on skylake's release could end up costing you more.

I'm quite likely to build a new PC myself around that time (providing I don't get restructured out of a job but that's another story) but the only choices I'd make right now are what form factor, case, and power supply I want to go with and possibly storage. I'll be leaving MB/CPU/RAM choices until the new parts are around and there are maybe a few reviews to read and see what the tech sites have to say. I wouldn't buy an SSD now either, things seem to be moving to M.2 PCIe and away from SATA AHCI and choices are still limited and expensive. I'd really like a 1TB M.2 SSD onboard next build.

I have almost gone devil's canyon a few times already, only the imminent release of skylake and uncertainty in my Job have stopped me.

BrotherDragon
26-07-2015, 03:49 PM
I think you're right about quad channel support. Another issue, if DDR3L refers only to laptop builds what memory will desktop Skylake support? My comment about current DDR4 latency and timing shortcomings still make it a poor and expensive choice so does Skylake support DDR3 as well for desktops? As I recall DDR4 and DDR3 use different sockets which makes the memory type decision a one way only proposition with no way to choose DDR3 now and switch to DDR4 later without swapping the motherboard as well.
______________________________
"I'm trying to think but nothin' happens" -Jerome "Curly" Howard

dugimodo
26-07-2015, 05:37 PM
I believe the chipset supports both but it's up to the motherboard manufacturers how they implement that. They could put dual ram types onboard, it's happened before.
Mean time just wait and see what happens. Also latency always increases as speed does but generally it's still better to go with faster RAM, the 2 are related.

From a poster on Toms hardware http://www.tomshardware.com/answers/id-1922024/ram-latency-clock-speed.html
The CAS latency is given in cycles. So, a CAS9 RAM will take 9 cycles to respond and the CAS6, 6 cycles.

Now putting it together: the DDR3 2000 CAS9 will take 9/2000 seconds, which is equal to 0,0045 seconds, to respond while the DDR3 1600 CAS 6 will take 6/1600, which is equal to 0,0038 seconds, to respond. Thus, the 1600 one is faster.

BBCmicro
26-07-2015, 10:08 PM
The Tom's Hardware quote could be taken as referring to response only? Not sustained access. It could be like waking up a hard disc drive ie, fine after the initial access? I don't know.

I will probably go with DDR4 because (a) 2400 MHz is a standard speed for DDR4 without OC. Whereas I think the highest standard speed for DDR3 is 1600 MHz (don't quote me). That's a 50% increase. I appreciate that DDR3 will go to 2 or 3 GHz if you choose something that's overclocked

and (b) I don't want my choice of MB to be constrained to one that also supports DDR3.

The following link to Amazon shows that the price of DDR4 is not necessarily excessive:

http://www.amazon.com/Corsair-Vengeance-Systems-PC4-19200-CMK16GX4M2A2400C14/dp/B00S51XHUQ

BrotherDragon
27-07-2015, 02:49 AM
The Tom's Hardware quote could be taken as referring to response only? Not sustained access. It could be like waking up a hard disc drive ie, fine after the initial access? I don't know.

I will probably go with DDR4 because (a) 2400 MHz is a standard speed for DDR4 without OC. Whereas I think the highest standard speed for DDR3 is 1600 MHz (don't quote me). That's a 50% increase. I appreciate that DDR3 will go to 2 or 3 GHz if you choose something that's overclocked

and (b) I don't want my choice of MB to be constrained to one that also supports DDR3.

The following link to Amazon shows that the price of DDR4 is not necessarily excessive:

http://www.amazon.com/Corsair-Vengeance-Systems-PC4-19200-CMK16GX4M2A2400C14/dp/B00S51XHUQ

I wish that Intel would release more information this close to Skylake's release date, we don't even know exactly when that will be. I'll go with DDR4 despite the timing issues but I'll plan to replace it when better memory is released. I'm tending to believe that i5 processors won't support quad channel memory but we just don't know and I'm not fond of using quad channel memory kits on a two channel board(see You Tube video below). Intel has only said that DDR4-2133 is supported so whether the DDR4-2400 memory you suggested will remains to be seen, my guess is that it will be. Cost is less of an issue than I originally thought, the memory you suggested is available on Newegg for only $130(see below).

https://www.youtube.com/watch?v=-D8fhsXqq4o

http://www.amazon.com/Corsair-Vengea.../dp/B00S51XHUQ

BBCmicro
27-07-2015, 09:54 AM
[QUOTE=BrotherDragon;1227911] Intel has only said that DDR4-2133 is supported/QUOTE]

Thanks for putting me right on that

My current memory is 1333 MHz so 2133 MHz would be a 60% increase on that. But I will go for 2400 MHz in my next build because it seems to be common overseas

I think in your situation I would go for 2 x 4GB because I don't think 4 cores (an i5)will use more than that.

My CPU is an i5-3570k and it got to about 7GB memory usage (see screenshot in your previous thread). That was with an application that only comes in 64-bit (ie, it is specifically designed to use lots of memory)

My own goal is to double my current speed to make 4k editing run faster. Part of my plan is to go from i5 to i7. That might double my memory usage and that's why I want 16 GB for Skylake. I've already implemented part of my next build - I've just invested in a good graphics card (GTX 970). So far I've only used about 50% of the card's capability. I'm hoping that doubling my CPUs will somehow feed the card more efficiently.

dugimodo
27-07-2015, 10:06 AM
If you do a lot of Editing BBC you might want to consider a Haswell-E setup, it will cost you more though.
The bottom end 6 core i7 5820K and 16GB of Quad channel DDR4 should still easily outperform skylake for anything that can use 6 cores and is available right now.

I looked into it myself but as a gamer it's really a waste of money and would not be any better than my i7 3770 I currently run. The only time I use my CPU fully is converting lossless music files to MP3 with dbpoweramp and as it takes about 30 seconds to do an album and doesn't happen that often I don't need an upgrade for that. It is cool though to watch the progress bar convert 8 songs at a time (8 threads) in just a few seconds each.

BBCmicro
27-07-2015, 10:28 AM
"12 CPUs" certainly sounds attractive! (along with quad channel memory)

But a small form factor is a bottom line for me. ATX cases are too big - they usually have room for multiple 3.5" drives. I went out of those heavy things years ago

That said, I worry if the cross-connections on a mini-ITX board are adequate to provide high performance. Again, I am hoping for efficiencies in the Skylake architecture (lanes?)

dugimodo
27-07-2015, 10:38 AM
http://www.computerlounge.co.nz/components/componentview.asp?partid=24839 :)

It makes some compromises but haswell-E in itx does exist. Only dual channel and hard to get coolers for (so they supply one but apparently it's loud). Quite pricey as well. If you wanted the ultimate multicore beast in an itx case though that's the one.

Myself I have gone both ways, grew to full tower ATX with sandybridge and shrunk to tiny itx for portability with ivy bridge.
Next build will strike the middle ground and be mATX with a corsair mATX case. I find itx a little restrictive in features at times but I am a fan of it in general.
I prefer the flexibility to maybe add a couple of extra drives or an add in card though.