overclocking a 2800+

[TIS]

im going to start a farm - all those cool pics made me want one too - i have 4 socket 754 boards and have just bought 4 of the new sempron 64 2800+ chips. now i need memory, what kind (speed) do i need to get to try and overclock these chips. im thinking if i can get 2ghz out of them i would be happy. (stock is 1.6) i know how to overclock the old xp chips but all this hyper transport stuff has kept me from overclocking anything new. should i get ddr 400 or 500 or what. help! :shrug:

[Mark620]

How about Patriot XBL ram it is supposed to be good to 533MHZ

[godofgorks]

well i'm sure ChasR will have some good suggestions about how high of memory is or isn't needed on these setups.

You can run a fast processor but then run a divider so your ram runs within specs. I've never had personal experiece with socket754 but do have a moderate tinkering with the HTT on a 939. If they are comparable I'd say that the divider on the fsb/mem won't hurt performace that much.

What boards do you have?

-headed of to find some good reading in the amd mobo/cpu forums-

will post back later

[TIS]

so ddr 400 is no good, get ddr 600 - newegg has these for 86 each (for 512) ill need 4 ouch...

[TIS]

the boards are gigabyte GA-K8VM800M

[godofgorks]

The basics of A64 overclocking, where I started learning about how HTT worked.

http://www.ocforums.com/showthread.php?t=391768

[godofgorks]

IMHO i'd go with some decent DDR400, and if the ram OC's some then awesome but if not just run a divider and keep in near stock.

Since you won't (or will you be transgering them from a Intel?) be folding QMDs you really don't need a lot of ram. 2x256 is all that's needed for and intel to fold QMDs so that should be more then plenty.

[TIS]

im an AMD guy - so what do i change in the bios to get to 2ghz? what times what is the stock 1600?

[godofgorks]

Here's another great read about A64 and all the stuff going on. Toward the bottom you'll find good info about what HTT is and how everything is built around that new mysterious thing.

http://www.ocforums.com/showthread.php?t=306418
EDIT: added thread... :)
EDIT2: Fixed thread....

I know exactly what your feeling, I was there when I build my first A64 and started OCing. Once you get the jist of it it's actually works out very nice.

I wish I was back at college and on highspeed, I could find so much more and look at stuff faster. On dial-up and trying the best I can. :)

Going to go do some research on those boards you have.

Are you going to run the farm diskless? If so I'd look into overclockix which is a OS specializing to folding. Thanks to Akraine and Overdoze for that.

http://overclockix.octeams.com/

[TIS]

im probably going to get hdd's for them - all ive ever tried is the console version.

[godofgorks]

Stock:

HTT: 200
LSD Multi: 4
CPU Multi: 8
FSB/HTT: 1:1 <---- Memory dividers

2ghz:
HTT: 250
LSD Multi: 3 assuming your HT bus can't do 1000 which is unneeded 750 will be fine.
CPU Multi: 8
FSB/HTT: 1:1 if you want to run your mem at 250fsb
..............5:4 if you want to run your mem at 200fsb

increasing the HT bus does not increase performance, at least noticably. You want to try to keep that close to what you started with using the LDT multi. HTT x LDT multi = HT bus speed. The testing that is done in the ones i linked to is just to see where your HT bus can handle so you can eliminate that from being a possibility of being the cause of instability later.

The basics you need

HTT x LSTmulti = HT bus
HTT x CPUmulti = CPU Speed

Memory dividers are a little more confusing, well explained in the second thread I linked to.

[TIS]

ok so i should get ddr 400 and try a divider? would it be more stable at 250 with the proper memory?

[godofgorks]

AS for my opinions of ram...

http://www.newegg.com/Product/ProductList.asp?Manufactory=&PropertyCodeValue=521%3A7965&PropertyCodeValue=523%3A8475&PropertyCodeValue=0&PropertyCodeValue=0&PropertyCodeValue=0&PropertyCodeValue=526%3A7869&PropertyCodeValue=527%3A7870&description=&MinPrice=&MaxPrice=&SubCategory=147&Submit=Property

Basically anything of a decent brand, at a decent level. I'd say you'd be looking at about $40 at the minimum per board on ram. Stuff below that I really woulnd't touch IMO.

Depends on what you want the ram to do. What speed and what latancies.

[godofgorks]

ok so i should get ddr 400 and try a divider? would it be more stable at 250 with the proper memory?

Bandwidth is the key here. Depending on how the memory performs, speed vs. latancy determins the overall bandwidth.

Tight timings at 200fsb can be better then loose timings at 250fsb.

I would say a majority of members run dividers on A64 systems and have no troubles. I don't know how your board runs with dividers. I'd say it's a personal opinion. Or try to find some benchmarks evaluating the differences between timings and latancy. These are big factors for folding on Intel, not sure how well they effect folding on AMD setups, but could only help I would assume.

Basically your down to that question now.

[TIS]

all the ones you suggest are dual channel kits - socket 754 is single channel why not one stick of 512?

[godofgorks]

all the ones you suggest are dual channel kits - socket 754 is single channel why not one stick of 512?

Sorry still somewhat vague to s754 but just using my s939 knowlegde to bridge the similarities.

If only single channel then go with one stick to save $$$.

Also comparing DDR400 to DDR500 there is a lot of the same chips in the memory its just that the manufacture took the time to test the memory to that level. When you buy the DDR400 you could have the same chips that the DDR500 has but just has not been 'set' to that timing and latancy.

It's a give and take as the overall desire is bandwidth on the ram which is both dependant on the fsb and the latancy that they can run at those speed.

On a side note, you could purchase 1gb dual channel kits (2x512) if you can get those cheaper. Then split them up to a single stick per rig. That way if you ever need to sell them or want to put them in a dual channel system you'll have pairs.

[TollhouseFrank]

one big difference between 754 and 939. ON 754, the HTT is more like the FSB. You can't set dividers and such the same as you can on a 939 board. Basically, PC3200 is more than enough. Set the RAM to 3200 in BIOS, and up the FSB/HTT past 200 5mhz/HTT at a time till it won't boot anymore. Then once you reach that point (and the max voltage that will sustain that point).... fiddle around till it is prime/memtest stable.... then once there.... start folding.... folding will REALLY stress it... so dont' be surprised if you have to lower yer OC 10-15FSB/HTT from max to get it folding stable.

[TIS]

frank, so would the memory be the limiting factor? if pc3200 is 400 mhz and i raise the htt bus to 220 that should give me 2ghz right? then shouldnt i get better than 3200 memory?

[TollhouseFrank]

frank, so would the memory be the limiting factor? if pc3200 is 400 mhz and i raise the htt bus to 220 that should give me 2ghz right? then shouldnt i get better than 3200 memory?


depends on the 3200 Memory. I've taken mine (Corsair Value Select) as high as 221 Stable (prime95 and memtest stable for 12 hours at a time each). However... my rig is unfortunately not folding stable at anything over 200 (not sure why). However... it depends on the RAM you get as to what it will OC to. I'd say get some cheaper PC 466 (if i just gave the right speed that is).... that should cover ya enough for the OC, but in my experience, MOST (not all, but MOST) RAM will OC at least 33-66mhz higher with the right voltage.

[godofgorks]

I think what he's saying is that the divider thing I was talking about doesn't really apply to s754 like it doesn on s939.

I saw someone mention on the egg about running a 5/4 divider so from that little piece I figured dividers were also a s754 thing. Another reason why I should stop reading the newegg customer reviews and get real ones on the forum. :)

So basically the memory you get you'll want it to be able to scale with your HTT 1:1. If your htt is running 250 then your mem is running 250fsb. (DDR500)

As I mentioned earlier though, you can take your memory and OC it up to DDR500 speeds. Just have to go about adjusting latancies and voltage.

Your CPUmulti is maxed a 8 on that chip so what ever you HTT is times your CPUmulti will give you cpu speed.

200 x 8 = 1600
220 x 8 = 1760
250 x 8 = 2000

[TIS]

thanks yall, i think i can do it now - ill post pics when i start building it. still not entirely clear on the htt thing but i think i got it enough... :)

[TIS]

ok so ddr 500 should get me there... thanks!

[TIS]

http://www.newegg.com/Product/Product.asp?Item=N82E16820146579

this is in my price range... ill give it a shot

[Enablingwolf]

I was going to input on this since it is a Gigabyte board which I have one. Also the 2800 which I have one.

One concern I had and looked into was the AGP lock. I looked and it appears that is a green light for you. Since VIA is not known to be a great over clocker. Least you have that.

For all of Gigabytes faults. They show the chipset right in the name.

I have yet to have a modern Gigabyte that could not pull 400Mhz+ on a overclock. In case you don't know. Ctrl+F1 is how you get to the advanced BIOS funtions. Since you are gettign great overclocking advice. I don't have much to add past what is already mentioned.

[TIS]

i did not know that about the advanced area in the bios - ill give it a shot. thanks!

[godofgorks]

This ram for ~$20 less is the same as the second ram and should provide the same results. Just change latancies and vdram of the first.

Comparison
http://www.newegg.com/Product/ProductCompare.asp?CompareItemList=N82E16820141108 ,N82E16820141123&SubCategory=147

DDR400
$42.24 ($37.24 after $5 MIR)
http://www.newegg.com/Product/Product.asp?item=N82E16820141123

same ram in DDR500
$58.21
http://www.newegg.com/Product/Product.asp?item=N82E16820141108

Same ram just speedbinned. That's only if you want to save a few bucks and try OC'ing ram. Otherwise go with DDR500 if you don't want to bother with that.

Just an example of manufactures speedbinning ram like they do processors.

[godofgorks]

I was going to input on this since it is a Gigabyte board which I have one. Also the 2800 which I have one.

One concern I had and looked into was the AGP lock. I looked and it appears that is a green light for you. Since VIA is not known to be a great over clocker. Least you have that.

For all of Gigabytes faults. They show the chipset right in the name.

I have yet to have a modern Gigabyte that could not pull 400Mhz+ on a overclock. In case you don't know. Ctrl+F1 is how you get to the advanced BIOS funtions. Since you are gettign great overclocking advice. I don't have much to add past what is already mentioned.

Way to be on the ball. That was something I completely took for granted.

Seems some people are complaining of the PCI/AGP not being locked on newegg though, not that it's the best source for info though. Conflicting information.... :/

[Enablingwolf]

Namely, I have to stress that VIA KT880 has finally acquired the so long-awaited option to clock the AGP/PCI buses asynchronously, which is also known as AGP lock.

http://www.xbitlabs.com/articles/chipsets/print/via-kt880.html

The KT880 is paired up with the VIA VT8237. :thup: So finding info on it can be cornfusing. It was the earlier rev's that were not locked down.

[godofgorks]

Chipsets
North Bridge VIA K8M800
South Bridge VIA VT8237

http://tw.giga-byte.com/MotherBoard/Products/Products_GA-K8VM800M.htm

Chipset is the k8m800 not the kt880....

No PCI/AGP lock = no to very little OC

[Enablingwolf]

I think the logic is the same on them. Let me double check to make sure...



I was wrong. The 800 has no locks on it. This board will be poor overclocker!!

[TIS]

ok now im getting confused again. i plan on using the onboard video - is it gonna crap out if i try to overclock it? that would suck, but i still would build everything and run it at stock if that is the case. but i would put cheaper ddr 400 if its not going to overclock.

[Enablingwolf]

You can overclock, but don't expect much out of it. Once it goes to far, it will loose sync and you will have mucho issues.

[TIS]

in that case i might as well keep it at stock speeds and avoid the headache. oh well, thanks for the info...

[Enablingwolf]

Well now you know, getting that cheapo RAM is the best option.

[godofgorks]

Just a proposition but since everything that will be used will be onboard and nothing in the PCI/AGP slots, would this still cause major issues?

If you overclock the slots but nothing is there to restrict them, or is the limitation between the board and the slots themselves?....

[TollhouseFrank]

TIS... what i'd do is go with the Cheapo RAM.... and see how much each individiual system will OC. Try them at oh... 210HTT/FSB first (if yer bios is anything like mine... it calls the HTT the FSB!! LOL). Then up it 5 at a time till it won't boot. Then up the voltages till it will... the RAM should take no more than 2.725 to get to 221 or further.... i'd estimate at most 2.75 to get to 230-235..... the CPU i'm not sure how much it will take (my board maxes at 1.55 so i'm not sure how much more the CPU can take).

[TIS]

well with the cheap ram at least it will run stock, i suppose i could fiddle with it to see if i can get a little more out of it. but at least i wont be dissapointed when i dont get anywhere near 250.

[TIS]

512 is enough right? there is no point in getting 1gb (even though the video may rob 32 of the 512) right?

[godofgorks]

no reason for 1gb, that's just overkill

as for 256 vs 512 that actually might be debatable.. depending on OS usage and the core....

I don't have the data to make a claim for either though

512 is just a necessity for intel to fold qmds

not certain on the ram needs of a sempron layer

[TIS]

512 it is then...

[TollhouseFrank]

for a sempron... i'd go with 512... keeps ya safe on the BP's... and also future proofing against any BP's that might pop up that require a ton of RAM (i've seen some of the BP's get upwards of 250mbs on my A64)

[Enablingwolf]

The no lock can sometimes corrupt data on your hard drives. Thats if you go to high. The hard drives run off the PCI bus. :(

I would do my testing with a Linux Live CD(overfoldix is a good choice). Or a drive that has no data of value, or have a backup image of the data as insurance.

Having a limit on your overclock should not stop you. You know the dangers and limitations. Myself I would see what the rig could do. Then if you get a poor overclock, blame it on the cheap RAM lol. If you get over 200Mhz come back and do a little dance.

[TIS]

i went with 512, since i already had a new stick in the box i went with this

http://www.newegg.com/Product/Product.asp?Item=N82E16820221005

these are going to be doing nothing but folding so all the ram (aside from the os overhead and video sharing) will be available for folding

[ChasR]

I've zero experience with 754 boards so I've no advice for you there. I do know that for all the work units out there for AMDs, latency makes a noticeable difference only on p147x/81 and there aren't many of those to be had. Memory bandwidth is only an issue with p147x/81 (needs around 3000MB/sec) so running multipliers won't make much difference on any other WU and perhaps not on them either. You don't need expensive ram for a dedicated folding rig. On Intel rigs running QMDs, the difference in performance running 2-2-2 vs 3-4-4 at the same speed FSB is only 7.2 %. If you put the money you save on ram into another rig, you'll make more points. Building dedicated folders, it should be all about bang for the buck. Four lowly $500 XP-M socket A rigs always trounce a $2000 A64 X2 4800+ rig given the same WU. Someone else can figure out if the cost of electricity swings the bang for the buck in this example, but the point is quantity generally overcomes quality in folding rigs.

[TIS]

yeah i see about the highest end stuff not being worth the money, but i think there would be a lower limit to cost effectiveness due to electricity. at some point, building a cheaper slower rig wouldnt make sense over a faster one. i guess somewhere in the middle is the best.