i7-5775C average IMC ceiling?

[Tropick]

Recently bought an i7-5775C for an overclocking side project. Found some cheap DDR3-2400 memory to try and get the most out of the platform however I'm having trouble getting the system to POST after loading the 2400 XMP profile. Realized I failed to consider that the non-"E" Broadwell IMC might not be up to the task for such a high frequency. Even raising the SA voltage to 1.18 and analog/digital voltage offset to +.150 it still fails to post at 2400. Only when I loosen the timings and set the multiplier to 21.33 (DDR3-2133) am I able to get it to POST.

Might be a long shot here but does anybody have experience with memory overclocking on Broadwell-DT and if so where do you find the IMC tops out at?

 

[Harlow]

I've just installed a similar i7-3770K in an old PC. I might try a few XMP tweaks tomorrow if I have time.

 

[Redwoodz]

The most info I have ever found on DDR3 overclocking in one thread is here

https://www.overclock.net/threads/ocn-ram-addict-club-gallery.1268061/#post_19304106

It's quite long but there are tons of insights inside.

 

[Harlow]

I've just booted my i7-3770K and it's currently running Windows Update. The RAM installed is DDR3-1333 Kingston and the fastest DDR3 I have is Corsair DDR3-1866 so I don't think I'm going to reach the dizzy heights of DDR3-2400.

According to CPU-World.com, the i7-5775C supported memory is DDR3-1333L and DDR3-1600L.
My i7-3770K is DDR3-1333 and DDR3-1600.

Are you running DDR3 at 1.5V or DDR3L at 1.35V with your i7-5775C?

I'm aware you can run DDR3L at 1.5V, but I'm not sure how standard DDR3 performs if run at 1.35V on a CPU designed for low voltage RAM.

XMP normally boosts RAM Voltage and with a low voltage IMC, you are may be expecting too much of the i7-5775C to POST at 2400MT/s.

Perhaps you'll have to accept relaxed timings at 2133MT/s. After all, it's well above the 1600MT/s rating of the i7-5775C.

 

[ShrimpBrime]

This may greatly depend on a few things the capability. Such as Amount of memory. Single rank or dual rank, number of Dimms installed, Memory IC and so forth and of course a good motherboard makes worlds of difference.

2133mhz at 9-10-9-27-36 1T would be groovy.

 

[:D:D]

Broadwell-E was predominately DDR4 although there are some Chinese X99 DDR3 variants.

A quick google shows quite a few 2400MT/s 5775C results, mostly CR2 aswell as other people reporting not being able to get that high. Some say core overclock affects DRAM OC. Maybe try manual with loose timings to start with?

https://www.reddit.com/r/overclocking/comments/107e6pu

Intel Broadwell Core i7-5775C & MSI Z97A GAMING 6 ,Intel Broadwell Core i7-5775C & MSI Z97A GAMING 6 ซีพียูอินเทลที่มี IGP แรงที่สุดประหยัดไฟที่สุดด้วยสถาปัตย์ 14nm โค๊ดเนม Broadwell : : Overclock (12/13)

Review Intel Broadwell Core i7-5775C & MSI Z97A GAMING 6 Intel Broadwell Core i7-5775C & MSI Z97A GAMING 6 ซีพียูอินเทลที่มี IGP แรงที่สุดประหยัดไฟที่สุดด้วยสถาปัตย์ 14nm โค๊ดเนม Broadwell

www.vmodtech.com

 

[Harlow]

Broadwell-E was predominately DDR4

Am I looking at the wrong i7-5775C here (CPU-World.com)?
https://www.cpu-world.com/CPUs/Core_i7/Intel-Core i7-5775C.html
The link above shows the i7-5775C as Broadwell-K (not -E) with DDR3L-1333 and DDR3L-1600, not DDR4.
I'm impressed that some DIMMs come with DDR3-2400 XMP. A bit like modern DDR5-9000?

 

[Tropick]

Hey everyone, thank you for the great advice in this thread! Here are some more specs for context:

The board I'm running the 5775C on is the Gigabyte GA-Z97X-Gaming 7. I'm running the chip delidded/direct die on Conductonaut TIM with a Noctua NH-U14S using an aggressive fan curve so temps are fantastic, lots of thermal headroom for the voltages. I have the thing stable @ 4.3GHz all-core @ 1.38v vcore, 20x eDRAM multiplier and 38x cache multiplier @ 1.18v ring. Might try pushing it a little harder but I've heard 4.4 is a unicorn and 22x eDRAM sees diminished performance in some applications.

The kit I've been trying to get running is a Corsair CMY32GX3M4A2400C11R 32GB kit. As I understand, getting 4x8GB sticks running at 2400MT/s is more challenging than getting 2x @ 2400 even with the 1.65v on the 2400 kit. Just received an offer from another seller for a F3-2133C9Q-32GTX kit at a pretty good price so I might resell the CMY32GX3M4A2400C11R and go with that G.Skill 2133MT/s memory at tighter CL9 timings and try and make up for it by pushing the eDRAM to 2200MHz. Not super familiar with memory overclocking so this is getting into "deep end" territory for me.

XMP normally boosts RAM Voltage and with a low voltage IMC, you are may be expecting too much of the i7-5775C to POST at 2400MT/s.

Perhaps you'll have to accept relaxed timings at 2133MT/s. After all, it's well above the 1600MT/s rating of the i7-5775C.

Yeah that's what I'm starting to think too. I have the SA/IMC @ a +0.150v offset which to my knowledge is "getting up there" voltage-wise so if I'm not able to crack 2400 with this offset I might be chasing a lost cause. At this point I'm thinking of just going with the G.skill kit previously mentioned and tightening it as much as reasonably possible. I really wish I could manually adjust memory voltage with this board... So far it looks like it only accepts whatever voltage is set in the XMP profile or default 1.5v..

Am I looking at the wrong i7-5775C here (CPU-World.com)?
https://www.cpu-world.com/CPUs/Core_i7/Intel-Core i7-5775C.html
The link above shows the i7-5775C as Broadwell-K (not -E) with DDR3L-1333 and DDR3L-1600, not DDR4.
I'm impressed that some DIMMs come with DDR3-2400 XMP. A bit like modern DDR5-9000?

Yeah it's definitely not an -E, but from what I've read there's some disagreement on what the actual variant code is. Wikipedia calls it Broadwell-DT for "desktop" but some forums call it Broadwell-K because it's unlocked just like a K-series chip. I've also seen it called Broadwell-C to denote the inclusion of the Crystal Well eDRAM die too. But yeah this has been a very educational experience when it comes to DDR3 OC. It sounds like most people had 1600-1866 memory from back then and anything over 2133 was getting into enthusiast OC territory. I went straight for a manufacturer-binned 2400MT/s XMP kit because "it should just work, right?" but I was rapidly humbled when I found out that with speeds this high, the silicon quality of the chip's IMC has a serious impact of being able to run these speeds stably (or in my case at all).

 

[:D:D]

Am I looking at the wrong i7-5775C here (CPU-World.com)?

No, not at all. Broadwell-E was mentioned in the OP and I was just adding a bit of info.

I'm impressed that some DIMMs come with DDR3-2400 XMP. A bit like modern DDR5-9000?

Expensive back then, best I could afford was PC3-16000 SO-DIMM in order to get a few more hwbot points. Only single rank and 2000MT/s but could overclock to 2400MT/s at 1.35V.

Higher DDR3 available and cheaper these days.

 

[Beginner Macro Device]

i7-5775C doesn't have a particularly well optimised IMC mostly because it's offset via huge L4 cache.

2200 MT/s is usually the ceiling, occasionally you can hit higher than that but I'd rather choose 2000 sharp and call it a day. There's no reason to push it anyway, this CPU needs lowest latency possible, bandwidth is not a bottleneck here.

 

[:D:D]

Before BDW some Haswell variants also had the 128MB of L4 cache, they were codenamed Crystalwell. Some smart guy developed and made an LGA 1150 interposer for them so the BGA CPU's could be run on desktop boards. Some reports stated the IMC was stronger than the traditional desktop CPU's although high rate DDR3 became less important due to L4 cache.

A 2666MT/s result

Intel Core i7 @ 4804.04 MHz - CPU-Z VALIDATOR

[xwitc5] Validated Dump by DESKTOP-5IU8Q2S (2019-11-16 15:57:49) - MB: EVGA INTERNATIONAL CO.LTD 111-HW-E872 - RAM: 16384 MB

valid.x86.fr

Perhaps being a mobile premium CPU helped, who knows.

 

[sn2x]

I ran 2400 MT/s on mine. Can't say the average though since I only used one of them for any extended period of time (2016-2018).

 

[Tropick]

Quick update, got the new 2133MT/s F3-2133C9Q-32GTX kit up and running. Let MemTest86 chew on it for ~10hrs overnight and no errors were detected at the stock 9-11-11-31 XMP timings. Pretty happy with this especially since it's a 32GB kit which I understand is a little more difficult to get stable than 16GB. I might try and tighten the timings down a little bit if I have some free time. Next step is going to be redoing the CPU/Ring/eDRAM OC. Hoping I can still hit 4.3 but I have a sinking feeling 4.2 might be where it tops out now as it was barely stable at 4.3 with the previous 16GB 1600MT/s kit. Thanks for the assist everyone. I'll probably list the CMY32GX3M4A2400C11R on the buy/sell sub here soon if anybody would be interested.