FSB 235, what RAM?

Newegg is replacing my bad RAM and giving me the chance to change it. I've got a P4 2.8C that will OC to 235fsb. What RAM will run best at 1:1?

Thanks, as always it's much appreciated.

KV

PS. Newegg has the GeIL Ultra Platinum PC4000 500MHz Dual Channel DDR Kit. Is this what I want. Does PC4000 run sweat at 235fsb?

The fastest route for you is to volt mod the motherboard and run BH5. It will allow tighter timings and increased PAT effectiveness as compared to PC4000 running the same fsb. You can get to 225fsb 2-2-2-5 pretty easily on 2.85V with BH5, and to 235 with 3-3.2V. This is the fast way, and it's cheaper to boot.

OK, good option. Might do that.

My second option, PC4000. Is running it at 235 and 1:1 running it under spec? How do I figure out the numbers for it?

Thanks.
KV

Volt mod - do you mean just increase the power to RAM in the Bios? Sorry, just learning RAM OC here.

Newegg has Buffalo Technology 512MB 6 Layer PC3700 DDR Memory Module 32X8 (Micron Module), DD466-512MC - OEM
Is what you're talking about? Can I run them as Duals?

Thanks for all the info.

Could always try RMAing that Black Level 2 to mushkin. If you are going the BH5 route again, mushkin is one of the few makers that'll give you BH5 for sure. Course, I too have some Black level 2 that won't run at its rated speed. So I can understand wanting to change brands.

You've both already got excellent ram, but you just need to put more voltage on it. As created, the P4C800 only delivers 2.85V and the IC7 2.8. This isn't enough for 2 512MB B5 sticks. It will do with 256MB sticks, and that is what Mushkin is assuming in their rating of the ram as PC3500. When you go to 512MB sticks you have to increase voltage to 3+V to pull it off. You will find this trait consistant with any BH5 based module, it is the nature of the beast.

By volt-modding I mean to modify the motherboard to increase the maximum voltage delivered to the ram. This is easily done with either the P4C800 or IC7, however it does require a good soldering iron and a steady hand.

Thanks larva. Good advise. I saw a post about how to mod your board that way. I'll hunt it down.

KV

I've not posted anything on the asus board, as I use the abit. But the asus mod is if anything easier than the abit. Although some manage to make it sound a lot more complex than this, all you are doing is appying voltage to one leg of the regulator IC responsible for the Vdimm. You do this by soldering a wire to one leg of the IC, connecting the other end of your wire to a potentiometer (variable resistor), and then hooking the other pole of the pot to a 12V source (I've even seen people use the fan header for this). You can find full details at the xtremesystems forum, in the Vmod section.

The abit mod takes a bit more dexterity. On the abits you remove a surface mount reisitor in the feedback circuit for the vdimm, and repalce it with a pot or a roughly 400 ohm fixed resistance. I used a 390 ohm resistor on my board. Reversing the mod is as easy as removing your 400 ohm resistor and bridging the two contacts with a sloder blob. The resistor in question is labled R50 on the IC7.

With either board you must have a very strong 3.3V rail on the power supply to prevent fluctuations in the Vdimm at 3V or above.

sorry to be off topic a little, but are you saying that its basically impossible to get good speeds and good timings with only 2.85 volts?

No, what I am saying is it is the limiting factor given today's ram, chipsets, and cpus. Running 512MB dimms on a 865/875 chipset makes it that much more profitable to increase the voltage. For most users looking to increase their memory-limited oc, increased memory voltage is the key.

Just thought I'd thank you larva. After reading your posts, and searching the forums a bit, I found that 2.7v (which I run at 200mhz anyways, windows won't boot with less) + disabling the last 2 GAT settings allowed me to run 217mhz with street racer or F1 enabled (although street racer was faster for some odd reason). I can only imagine what more voltage will do for this memory.

Cool, glad to hear you are making progress. You are correct in that in most cases those last two GAT fields must be disabled. And I have seen cases where SR (or even Turbo) is faster than F1, but mainly when the more is being asked of the memory than it can deliver. F1 forces 2-2-2-5 memory timings, where SR uses 2-2-2-6. It is very likely that with say, 3V on your memory that F1 would be the fastest setting.

When I had CH5s Turbo was fastest, but when I switched over to BH5s, disabled the last two GAT fields, and put 2.97V to my ram F1 became the clearly fastest setting. Don't fear to increase it to 2.8 or even 3V, it won't hurt the ram. The only thing I caution is not to use the suspend to ram (S3) function, as the high voltage in combination with the lack of case airflow may be damaging.