Core i7 - Does the memory NEED to be bought in threes

[whodatrd]

Just purchased a refurb Dell Core i7 920 machine that has 6 slots for DDR3 memory. The machine came loaded with 8 gb's of ram installed as follows:

Slot1 - 2gb PC3-8500F (533 MHz)
Slot2 - 2gb PC3-8500F (533 MHz)
Slot3 - 1gb PC3-8500F (533 MHz)
Slot4 - 1gb PC3-8500F (533 MHz)
Slot5 - 1gb PC3-8500F (533 MHz)
Slot6 - 1gb PC3-8500F (533 MHz)

Seems to me that it would be a good idea to get one more 2gb stick for Slot 3 so that I can take advantage of the i7 triple channel memory. So I guess my question is:

Is that a correct assumption. Is difference that great between having them in pairs vs. threes?

Thanks!

 

[TemjinGold]

Well, to be honest, I doubt you'd notice the difference unless you were benchmarking.

 

[taltamir]

id sell all of those sticks on ebay and get 3x2GB matched triplet.

 

[whodatrd]

One of you says the improvement is only slight, the other says sell em on ebay and buy matched triplet. Hmm.

Taltamir, do you think the difference would be worth the effort? Wouldn't it be just as easy to just buy one more 2GB that matches the other two 2GB chips (PC3-8500F (533 MHz))? That way I'd have three matching 2GB chips and three matching 1GB chips for a total of 9GB matched triplets... or am I confused about how all this works. Please advise, I'm completely new to this i7 thing.

Thanks!

 

[taltamir]

i was actually thinking more along the lines of:
1. monetary value of the ram
2. electric usage.
3. heat
4. load on memory controller, reducing effectiveness of overclock.
5. potential issues caused by obviously mismatched pieces of ram thrown about willy nilly.

I think you have 3 matched pairs... one 2x2GB pair, and two seperate 2x1GB pairs. see if you can match them from serial numbers.

I agree that from pure PERFORMANCE perspective, the difference is negligible... but I think you might even manage to break even or save money doing what i described.

for example, I just sold my Q6600 for 160$ on ebay, and bought a used Q9400 for 165$ on ebay. I calculated the power difference cost to be at LEAST 10$ a year at the absolute minimum... plus I get a faster CPU and a cooler running one to boot.

 

[TemjinGold]

Well, if he did what you described, he might manage to break even but he'd also just have less ram. Why would you want to maybe break even and end up with less ram when the difference in performance between triple channel and non is really negligible?

 

[taltamir]

so is the difference between 6 and 8GB... by the time it will not 1GB modules would be worthless and unsellable. but 3x2GB would still be useful and he could upgrade with another 3x2GB in the now FREE slots for a total of 12GB of ram.

 

[TemjinGold]

Dude, you're missing the point. You're asking the guy to maybe break even and possibly fork money out with a net result of having less ram. He's getting LESS than what he has with the money and effort spent. I'm not saying 8 gb is necessarily that much better than 6. What I am saying is that it's retarded to sell and buy (possibly losing money) only to end up with less ram.

 

[taltamir]

you are missing two things. While he has less ram overall, he has MORE open ram slots... when he actually NEEDS TO he can upgrade from 6 to 12... if he keeps what he has he will have to throw away all his current ram and buy the whole 12GB.

I need 8GB of ram right now, most people do not.

He gets much faster ram bandwidth. While it does not translate to huge speedups, it is not completely insignificant.

And he would lose a lot more money later on if he doesn't do this now. There is a "right time to sell", and now is the right time to sell 1GB and get 2GB kits.

I would BET that his overall performance goes UP if he does what I suggest, not goes down. And he will save money in the long term.

 

[TemjinGold]

OP: I'm done trying to talk sense into the other guy. As it stands, if you want less ram for money and hassle, do what the other guy says. When 1gb modules are "worthless and unsellable" as he says, 12 gbs won't get you anywhere either and 2gb sticks won't be very sellable (you can still sell really small DDR/DDR2 modules today even.) If the triple channel thing really strikes your fancy, it would be much better to do what you originally wanted, which is to sell one 1gb stick and replace it with a 2gb stick. At least you would be getting something for the money you spend in that situation. Bottom line is, you aren't likely to SEE an improvement in performance doing what he says but it will probably cost you and you will end up with less ram.

 

[taltamir]

is he not working in SINGLE channel mode right now because of how mismatched his ram sticks are? single to triple chanel is quite the difference in ram bandwidth, I said before it wouldn't be much of an upgrade but I take that back, it should make some difference.

you can still sell really small DDR/DDR2 modules today even.

I tried, it doesn't even cover the cost of shipping, or if it does, it is not worth the time for less than 5$ "profit". So its not that it is unsellable so much as not worth your time.

 

[whodatrd]

Its a good healthy discussion on the topic (sorry I didn't catch the notification of replies). I'm fine with running with three 1gb sticks and three 2gb sticks for a total of 9gb for now (I don't forsee needing more than that for a while).

If I sell one 1gb stick and replace with a 2gb stick of the same specification as the other 2gb chips will that let me achieve triple channel bandwidth, or do the sticks need to be IDENTICAL as in the same exact manufacturer (matched pair)?

If they have to be identical than I need to by a kit with 3 matched 2gb sticks, but if they can simply be the same specification then I can get away with buying just 1 new 2gb stick which is easier and quicker.

 

[Yellowbeard]

Originally posted by: whodatrd
Its a good healthy discussion on the topic (sorry I didn't catch the notification of replies). I'm fine with running with three 1gb sticks and three 2gb sticks for a total of 9gb for now (I don't forsee needing more than that for a while).

If I sell one 1gb stick and replace with a 2gb stick of the same specification as the other 2gb chips will that let me achieve triple channel bandwidth, or do the sticks need to be IDENTICAL as in the same exact manufacturer (matched pair)?

If they have to be identical than I need to by a kit with 3 matched 2gb sticks, but if they can simply be the same specification then I can get away with buying just 1 new 2gb stick which is easier and quicker.

The "identical" part is what is unpredictable. Ideally, yes, all 3 or 6 modules should be identical. However, if you mix and match odd modules the ONLY way to know if they will work is to install and test them. It will probably work as the i7 memory controllers seem to be pretty flexible so far. But, there is no guarantee.

For simplicity, ease of use, and overall system nirvana, taltamir made some good points IMO:

i was actually thinking more along the lines of:
1. monetary value of the ram
2. electric usage.
3. heat
4. load on memory controller, reducing effectiveness of overclock.
5. potential issues caused by obviously mismatched pieces of ram thrown about willy nilly.