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Discussion Starter #1
So I knew this might happen but it's a chance I had to take, maybe someone can help.
I've been running this on my 4690k & z97 Asus MKII:
4.7Ghz @ 1.3v core
4.3Ghz @ 1.235v cache
1.8v input
8Gb PNY (orange) 1333Mhz 9-9-9-24 overclocked to 1800Mhz on stock timings with 1.65v
VRM is set to optimized with the middle LLC setting.
I've ran lots of Prime95 to get this where it is, been using these settings for months and never had an issue.

I decided to add another matching 8Gb kit of ram and found it on eBay for under $35 shipped so now I have 16gb (high time lol).
Now I can't get the ram to OC worth a damn, each kit will run 1800Mhz on stock timings separately but not together. In fact I can't even get 1600Mhz to boot, I have them set to 1400Mhz now and it passed Prime blend for over an hour.

So what can I do to get both kits to overclock together? I feel like I'm missing something, all I've messed with is the speed, voltage, timings and I've set the RAM VRM to full phase mode.
Perhaps instead of trying more clock speed I should run 1400Mhz with tighter timings? Not sure how to hone in on this.
I don't really care if I have more clockspeed or less latency as long as the CPU can get data faster lol.
 

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Tinkers With Rigs
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This could be tough without a second set of memory from a different vendor to test. If I were to speculate it seems like a power delivery issue to the RAM when all 4 slots are populated, thus the need to downclock to be able to boot.

I didn't see any PNY listed on the QVL for your board but maybe the list is old or I missed it? The obvious answer is up the voltage but I'm not sure what your exact model is on the RAM.
 

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Discussion Starter #3 (Edited)
Yeah it's not on there, I've always had to do things manually. I think you're right about there being a power issue though, I'm just not sure what to change. Then again ram uses so little power. I can boot with all of them running 1.65v so I think it could be the CPU's IMC that's letting me down.
This is the ram:
https://www.amazon.com/PNY-1333MHz-PC3-10666-Desktop-MD4096SD3-1333/dp/B004D7NAOO
Bought it for a Dell years ago from BestBuy so I could play games on it with a 750TI (first rig). I built this rig and the ram just never got replaced, now with the pricing like it is and DDR3 being obsolete I couldn't justify buying a single 16Gb kit.
 

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Tinkers With Rigs
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Ha! I googled "Orange PNY" and that's the kit that came up. I hear ya on the RAM prices. Been wanting to go up to 16GB myself but can't justify it.

Hell of a deal you got on that matching set though. At 1400 you're still above the 1333 rating and it would be interesting to see what you can do with tighter timings. Benchmark the 8GB at 1800 and then the 16GB at 1400 (or whatever) and some tighter timings. Could be surprised, could be a total wash, but that's why we do this eh?
 

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AMD OC'ing Enthusiast
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Its a somewhat normal experience to lose overclocking potential with more ram slots in use. IE, if you were to have 2x8gb versus 4x4gb, majority of the time, the 2x8gb config will clock better.


I suggest going through your ram timings, and if you have access, the secondary/sub timings. try increasing your tRAS by 1 or 2 clock cycles, and increasing your tRC by 4-5 cycles.

NEgligable performance effect, but generally a good stability boost.

with 4 slots in use, the generic rule of thumb of CL+tRCD+tRP = tRAS is needed a bit more often, as well as tRC sometimes needing to be higher/bigger than the result of tRAS+tRP. hammering voltage at the sticks doesnt always work.

Give it a shot.

Might also need to lower your cache frequency slightly. If its currently at 4.3ghz, try 4.0ghz and see if it helps at all.

tRFC should be higher with more slots in use. For my AMD machine, I can run in the high 100's with 2 sticks. with 4 sticks, i have to run in the 300's. a noticable performance difference on the amd FX lineup when you need to squeeze every last ounce of effort out of the system. Not a big deal on intel architecture
 

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Discussion Starter #6
OK I hear you both. I'll do some fiddling around and see what happens. There are gobs of voltage settings on my board and a long list of timings.
I'm pretty sure I can't boot at 1333 cas 8 though so I might be screwed lol.

Yeah the cache was something I'd considered and I think when I got the first few fails I tried stock speeds with the ram OC'd and failed. I'll keep trying things.
 

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I know I am going to sound like 1000 other posts on the internet with this, and you already know it..but here goes.

Memory kits, even same brand and model are binned specifically to be run in the configuration they were sold. Putting 4 sticks that were not binned to run as 4 sticks is a crapshoot. The loads and subtimings change when 4 sticks are in use vs. 2. Anything over JDEC should be considered a lucky draw.

I look at like putting tires on vehicles...2 sets of motorcycle tires are not going to behave as well as a single set of car tires. I know that isn't a perfect analogy because a 4 wheeled motorcycle isn't a car...but...

From one overclocker (who has beat their head against mixed kits) to another: I would personally try loosening the timings some, and go for RAW Mhz first, then come back and see if you can get the timings down. It was my experience with DDR3 that the further I got from 1333, the happier I was.

Raja made a lengthy post about it over at the ROG forums...https://rog.asus.com/forum/showthre...e-memory-kits!-The-meat-and-potatoes-overview
 

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Discussion Starter #8
I know I am going to sound like 1000 other posts on the internet with this, and you already know it..but here goes.

Memory kits, even same brand and model are binned specifically to be run in the configuration they were sold. Putting 4 sticks that were not binned to run as 4 sticks is a crapshoot. The loads and subtimings change when 4 sticks are in use vs. 2. Anything over JDEC should be considered a lucky draw.

I look at like putting tires on vehicles...2 sets of motorcycle tires are not going to behave as well as a single set of car tires. I know that isn't a perfect analogy because a 4 wheeled motorcycle isn't a car...but...

From one overclocker (who has beat their head against mixed kits) to another: I would personally try loosening the timings some, and go for RAW Mhz first, then come back and see if you can get the timings down. It was my experience with DDR3 that the further I got from 1333, the happier I was.

Raja made a lengthy post about it over at the ROG forums...https://rog.asus.com/forum/showthre...e-memory-kits!-The-meat-and-potatoes-overview
Yeah I know and I knew it was a gamble when I bought it but it's $30 and now I have options lol, 16gb of 1400 or 8gb of 1800.

9-9-9-27 didn't get me to 1600
8-9-9-24 is my best benchmark with this configuration

Not tried anything above stock timings yet and I'm not playing with it all night lol, I have some games to run. If 16gb of slow ram is less stuttery than 8gb of faster ram I'll have the answer I set out for. 144fps minimums are hard on 3 year old CPUs lol.

Thanks for helping guys, I'll play with it again another day.

EDIT: Which is more important, fast cache or fast ram?
 
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