T6400 in Toshiba Satellite L355-S7905

This site helped me immensely in trying to figure out what would work, so I figured I should join and report the outcome of my swap. The original CPU that I removed was a Celeron 585 (single core, 2.16 ghz, slow as a snail), and I just finished replacing it with a Core 2 Duo T6400. Chipset for this computer, according to CPU-Z, is GL40. Aside from the minor inconvenience of being forced to re-install windows (after the swap, it refused to go beyond the startup screen without a BSOD), but now that that's out of the way, everything is working as it should.

BIOS is the latest version from Toshiba's website, 2.10 I think. After the swap, battery life idling at the desktop has increased from 2 hours 30 minutes to 3 houts 20 minutes, as well. I got the CPU on eBay for $40, and IMO that's money well spent.

 

Good to hear that it went well.

Also, increased battery life is good, as a lot of the Celerons don't have Speedstep.

 

wow, I never knew T6400 could be that cheap!
Nice upgrade!

 

Hm

Running Prime95 for any length of time gives me "Hardware failure detected" on one or both cores, followed quickly by a BSOD. Faulty CPU, or laptop unable to handlet it?

 

Are you using a notebook cooler?

Do the temps get high (that would cause the errors)?

 

The errors happen within 30 seconds of starting the test each time. Most recently, temp was 68 at the time, slowly but steadily increasing. Fan was running but not on high.

System seems otherwise stable, but all I've done so far is install windows and other software.

Only thing I can think of is that the voltage range of the original Celeron is 0.95-1.30V, and that of the T6400 is 1.000V-1.250V. Would a BIOS that is able to recognize the new CPU not be able to handle the voltage correctly?

Also, the Celeron used 31 W while the T6400 uses 35, but the same series of laptop also came with a Celeron 900, which has the same wattage (35) as well, so it should be able to support it.

Idle temps for the processor are 47 and 48 degrees. When running Prime95, the temps stabilize at around 69, with the fan still not running at 100%.

CPU-Z lists the voltage as 1.000 when idle, and 1.150 when the test is running.

 

Running Prime95 some more using small FFTs instead of Blend as the testing method produces stability, at least for a much longer time than using Blend did. Perhaps my RAM is now the point of failure?

Looks like it might be. Apparently the system is clocking the RAM at 800 mhz, and being that the original CPU had an FSB of 667, I highly doubt the memory was meant to take the overclock. Is there any way I can go about fixing this, without buying new RAM?

 

The CPU's FSB and the RAM modules speed are not connected (I'm pretty sure).

Can you try the tests with one stick of RAM? Switch them if it BSOD's again for you and see if you have at least one stable sodimm module.

 

The tests failed anyways after about 10 minutes even when I manually set the memory usage to 0. Looks like either the CPU is bad, or for whatever reason my computer is not capable of supporting it.

 

Actually, they often are. The frequency of a CPU FSB must often match the frequency of the memory bus for proper operation. This is why the FSB boosting programs like SetFSB and all those often end up with unstable memory; by pumping the CPU FSB, they pump the memory bus too. This usually isn't a big problem, because in the Core 2 days, CPUs were quad pumped (the FSB frequency was actually 1/4 of the listed amount, because it performed 4 transfers per clock cycle), while memory was only "dual pumped" (DDR, double-data-rate) so something like an 800 MHz FSB (actual speed 200 MHz) could run up to DDR-400 (memory bus 200 MHz). DDR2 doubled this again, so the same memory bus speed could run DDR2-800 (PC2-6400). DDR3 doubles it yet again, but since it's become more and more tied to the on-die memory controllers of i7 and Phenom II, I don't know that the old comparisons hold as true anymore.

From the sounds of it, if that's the problem, maybe a shift to PC2-6400 might fix the issue (if DDR2 fits!), but I really have no idea. Overclocking isn't my thing.

 

It isn't. The tests failed anyways when I set the memory usage to 0, and my ram IS DDR2-800 (CPU FSB is also 800). I'm at a loss what to do, except to return the CPU and try something else.

 

Hmmm... I don't know specifically for the OP, but my P8400 CPU has a 1066 Mhz bus speed rating and I'm running 8GB of DDR2-6400 (400 Mhz) so it doesn't seem to need it matched.

 

No settings in the BIOS?

Maybe you could use crystal CPUID to over-volt the CPU towards its proper voltage (maybe its too low)?

Another stab in the dark - does the thermal paste need to 'set' before it does its job properly?

 

Nothing of any value in the BIOS

Thermal paste should not need to set, I've installed CPUs in two desktops and fired them up and stress tested them immediately without issue.

 

Did you try crystal CPUID?

What about a possible upgrade to your BIOS (from the same manufacturer, but a model that supports the CPU you're using)?

 

I downloaded it, but I haven't the slightest idea how to use it. It's the newest version of the BIOS that is available. I'd most likely brick my computer if I tried to use one for a different model.

 

First, make sure that you have downloaded the proper version (32bit or 64bit).

You can lower or increase the voltage with Crystal CPUID, look in the function menu for the option Intel Enhanced SpeedStep and make sure you click the Enable Change Voltage button.

Hope this helps, good luck.

 

Still doesn't work

Going to put my old CPU back in and return this one, I'm afraid

 

Heading slightly off-topic here, but I think the bus speeds are still matched, it's just that your RAM speed doesn't saturate the memory bus speed. Both your FSB and memory bus speeds will be at 266 MHz, it's just that the RAM won't achieve the maximum transfer rate, much like you can often install slower speed RAM into your system.

Still for the OP, I'm sorry to hear that the upgrade didn't work out for you.

 

I put the Celeron back in for now. I'd still really like a dual-core of some sort, though, as I use the laptop for video editing.

Through google, I've found out that a very similar model (L355-S7902) shipped with a T3400 in it. As the BIOS for all L355 models is the same according to Toshiba's website, might I have better luck with this processor?

 

I've put T7250 inside L300, so I think you're good to go with Merom and earlier series of Penryn (T8xxx or T9300)..
For your issue,
It could be the problem with BIOS support for T6xxx or bad cpu.

 

Does anyone know for sure if a T3400/T5800 will work in my laptop instead? There are Satellite L355 models out there with both of those, but they have different model numbers. The BIOS for all L355s is the same, but after expecting this one to work and finding out that it didn't, I want to be as sure as I possibly can be that what I do next will work.

EDIT: Ok, I really don't know what's going on. The BIOS I downloaded from Toshiba's website says it's for Satellite models L300/L305/L350/L355, and some of those models come stock with a T6400. So it seems unlikely that it's a BIOS issue, or even a motherboard issue (same BIOS means same motherboard, no?), which leaves faulty processor.

 

I don't think same BIOS necessarily means same motherboard; it's not quite the same, but people have been flashing the BIOS from various graphics cards onto different graphics cards to change their voltage and clock settings.

 

I'm essentially just trying to convince myself that a T3400 (stock processor in the L355-S7902) will work in an L355-S7905. I wish there was some way to confirm it without having to actually try it.