Overclocking E6550 vs 6750

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Thanatos421

Thanatos421

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Mar 26, 2007
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Put together a e6550 on an Asus Maximus Formula last night. Fired up perfectly, installed Windows, and all my lovely overclocking tools (Prime 95, CPUz, Core Temp, SpeedFan). Once I got all drivers updated, I started in on my overclock. Got it to 3.0 easily of course, pushing 1700 rated FSB at stock voltages, and DDR2-1066 running @ 1080.

I know that the 6750 is usually going to get better results due to the higher multi, but with a 7 multi, what can I expect to reach with the 6550. It's running at 428 FSB for 3.01Ghz right now. If I shoot for 3.5ghz, then I'll have to set FSB to 500, and have an effective 2000mhz FSB. Think the board can handle it? RAM shouldn't be an issue, 4 gig of Corsair Dominator DDR2-1066.

With a rated FSB of 2000, you think I'll have to bump the chipset voltage? I'm trying to avoid that alltogether and honestly, the only voltages I'm comfortable changing are the vcore and memory. If I can hit 3.5 w/o having to change the voltages (FOR CHIPSET), then yay, I'll be happy with that.

Opinions? Questions? Let me know if you need any more info.
 
The chip will do 500 FSB.

It won't do it at near stock voltage. Voltage requirements become exponential at a certain point.

My Q6600 needs:

1.248 at 3.0 GHz for stability.
1.264 at 3.2 GHz for stability.
1.312 at 3.4 GHz for stability.
1.35+ at 3.5 GHz (Haven't gotten it stable.. but it's a motherboard vDroop issue I don't want to push til I have cash for a replacement).
 
You guys didn't read at all did you 😛 I said the voltage that I didn't want to touch were the chipset levels. I know my limitations on core voltage, which is why I am comfortable changing it. Same goes with DIMM voltage. I've never tried such a large OC that I've had to fiddle with the NB, SB, etc voltages...so I don't want to mess with them now.

So, now that you may have a clearer picture of my question, what do you think the chipset can handle at stock voltage.
 
If you can find a pencil mod to eliminate Vdroop for that board you are set. I am currently running my E6600 at 3.45GHz with voltage set below stock (1.300v current vs. 1.325v stock) and I have no issues at all. This is on an ASUS P5B-Deluxe with a simple pencil mod. My voltages dont vary at all. Rock solid at 1.300v regardless of conditions or load. Before the pencil mod this was not remotely possible. I understand that this is a different chip and board but you would be amazed at how stable your voltage can be with a 5 second mod. It amazes me that manufacturers would not take this into account when fabbing the boards. Any ideas on that note?
 
I got it to 3.2 stable Prime 95 for 24 hours, 1.300v core. 1828 rated FSB, DDR2-1096. Wouldn't POST at 500 FSB, even up to 1.35 vcore. Tried 485 for 3.4GHz, no go either, even at 1.35. I believe my problem there to be the strange memory dividers that are available at that FSB. I couldn't get close to 1066 really at all at either 485 or 500. I could underclock the memory to right at 1000, but not sure that would be worth it. The closest choices available above 1000 were both over DDR2-1200 and I don't want to really over-volt the memory. I've had bad experiences even nudging memory up .01v.

Any ideas?

Thanks for the pencil mod idea, but this isn't my PC and he's already nervous that I'm overclocking it (tho I'm not sure why).
 
266 (1066) to 500 (2000) is nearly a 100% overclock in bus speed. If you're going to bump the FSB that much, you'll definitely need to give it more voltage. You won't be able to 500(2K) just on vCore and vDIMM alone. And don't worry so much: You've already figured out how far you can take it on stock settings. A couple 10ths bump in Bus voltage won't kill the board, and just might allow you to reduce vCore some.

Regarding the memory: I'd recommend the UNDERclock for the time being. Too many variables to work efficiently with all at once. Hit your FSB/CPU targets first. Then make the RAM work around that. Once you're settled on system speed you can play from there and decide if you like higher clock speed on the RAM or if tighter timings are the way to go.
 
It's actually 333(1333) to 500 (2000), but I totally agree. I knew that pushing the FSB that high would probably be my brick wall. Is there a resource somewhere that will tell me the default NB, SB etc voltages? The Maximus doesn't really denote the defaults.
 
I have a P35 chipset, and IIRC the stock NB core voltage is 1.3. And you shouldn't have to do anything to the Southbridge since you're a perfectly intelligent guy who's already locked the PCi bus at 100Mhz....
 
So, is the NB voltage the only one I would need to bump? I'm in newb territory here. Just wanting to make sure I do this right. Cause I'll have MY new one here in a week or two and it's almost the exact same system, but I'll be starting with a 6750.

Yes, PCI locked at 100 :)
 
The great thing about overclocking these 2 systems, is that these CPUs are totally temporary. I figured, if I absolutely needed to (on mine) I can push vcore a little more. The chip will be replaced in January with a Penny, so I'm not worried at all about long term effects on the current CPU.
 
I'm only "sort of allright in a n00b~ish kind of way" at this stuff. So I like to change as little as I have to at any one time - makes it easy for me to identify just how I screwed up. 😀

At the point you are at, I would have the RAM running at 1:1 knowing it's a little underclocked. I'd keep the voltage at the recommended for it's rated speed while playing - About 2.1v, yah? With the RAM safely settled: From there, start with the last known good overclock and bump FSB core voltage a 10th or two. Make sure that works, then go back to pushing FSB speed some more and see how far that gets you.

I know it's bad manners to mention outside forums, but if your maker doesn't have a good forum, you might want to swing over to the DFI forums and take some time to read through the "Out Of Warranty" section. Some of the guys there are serious benchmarkers: Check out the "3.6Ghz Super Pi 14m challenge" thread. It'll be specific to a DFI board, obviously. But there's good info nonetheless. Also, the 'New To Overclocking' area is good as well - Info on the math behind things, recommended tools, etc. http://csd.dficlub.org/forum/index.php
 
Thanks a bunch for the suggestions Scott! You have settled my nerves a lot regarding voltage changes. I've just always known that if one factor can "fry" anything, it's over-voltage, so I've been afraid to touch most of em.
 
No worries, sir. A 500 Mhz FSB is pretty aggressive, so good luck! 3.4~3.6 seems to be around the thermal limits on air. But you should be allright as long as you keep temps under control, adjust only one or two params at once, and don't get carried away with the voltages without double checking yourself. An extra 10th or two while dialing in will be fine. Your temperatures will let you know when you're going too far. Then once you've found settings that work, you can dial the voltage back down until instability creeps back in. Bump slightly from there. Then get out your tools and beat the snot out of the thing to be sure.

Oh - Running my little Q6 at 3.2/8multi/400fsb as a 24/7 setup. Works nice. It'll do 3.6 no prob, but starts getting a little warm and I want it to last until the next socket.
 
Woot! Stressing 3.4 as I type this. 3dMark jumped to 12200. 1.325 vcore for now, but haven't tried the ticks between 1.3 and 1.325. 1940 rated FSB, DDR2-970.

What was holding me back last night was the DDR frequency. These sticks can't handle over 1200 at 2.1v. NB is at stock volt still.

Gonna shoot for 3.6 now. At 1:1, that should bring the memory back to 1028MHz, and I might be able to tighten the timings a little in the end.
 
I have an E6550 in my new build. According to one of my oc programs (can't remember which right now), it said that my max (theoretical) cpu freq was 3.8GHz. Divide by 7 to get...cal it 543MHz. Your DDR2-1066 will be running at 1086MHz (assuming 1:1), which shouldn't be a problem. But at that speed you will need exotic cooling techniques. At2.8GHz, my cores get to 69C on stock cooling. I believe that 72C is the throttle point for temp control. Then again, it's your computer...

:sol:
 
At 3.4, my load temps never got above 55c. However, at around the 3rd hour of Prime95, it errored. Gonna try again after the weekend, give the chip a little more juice.

Ah, stock cooler. Disregard this if you read it before I woke up 😛 That seems really hot for 2.8GHz. I am using the Thermalright Ultra 120 Xtreme with a Scythe SFlex 120mm fan. Seems to be doing the job great.
 
So, at this point, I have 3.2 rock stable. Opinions on trying to push it more? Will 3.4 or 3.6 make THAT much real world performance difference? Is it worth the extra core voltage? The slower memory performance, higher temps, etc?
 
Personally, I'm gonna stay at 2.8 untill I buy a real cooler. and, IMHO, I don't think its worth the extra stress for 200 or 400 more MHz, since, at the top end, you have to put a lot more stress on the CPU for negligible perfomance increase. My original goal was 3.0, since setting for that only put a 60MHz OC on my RAM. But, with stock cooling, that's a risky speed.
 
It looks like 3.2 is the sweet spot so far. It allows the RAM to run at a little faster than rated speed, not sure about the ratio, the Maximus simply lists what speed the RAM will run at using the different dividers. FSB is screaming at stock voltage, and the CPU is running relatively cool. It handles Hellgate: London and CoD4 like a charm.

Now, I'll see if I can tighten RAM timings, and squeeze a little more clock out of his 8800 GT.

Then I get to build mine :) Should be able to get to 3.4 on the 6750 very easily. That's what I'm going to shoot for.
 



Personally, I think 3.2 is a 24/7 do-able, 'level-headed' target, for something like a Q66. That's a 25% processor boost on a 50% FSB bump. Yet it runs on stock or near stock voltages given a good Mobo, and stays well within even conservative temperature limits. {But that's what I decided for myself, so there's always a bit of the old Self-Serving Bias in seeing/convincing others to reach the same conclusions... 😛 }

Now, that's a bit more of a stretch for an E6550, but not out of the question. What are your voltages and temps? If you're within a couple 10ths of stock, and your temperatures are well under control, then you should be GTG.
 
At 3.2, all voltages are stock and temperatures look great. 3.4 looks like it might take 1.35 or more to get stable. Haven't had a chance to play with it since my last post. I'll try it tonight and let you know :)
 


Good luck.

Btw, drop it in a P5E... I've seen some 550-600 MHz FSB on 6550s on that board from people.
 
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