Dell precision T5400 max VRAM through PCI-E x16 slots

[mnw48]

i currently have a Dell precision T5400 workstation from ebay in temporary storage at a friends house, ive been buying bits for it also from ebay, but there are a couple of things im unsure of, one being the title of course, it mentions in the very small PDF file for the unit that it has 'Support for 2 PCI Express x16 Gen 2 graphics cards up to 150 watts and with up to 1.5GB
graphics memory...' can anyone clarify if this is just due to the testing at the time or can handle one single 3GB graphics card....? ive not yet bought a graphics card. iirc the unit has an 875W dell psu

also mentioned is 'Up to 32GB1 quad-channel architecture Fully Buffered DIMM 667MHz ECC memory; in 8 DIMM slots. DIMMs up to 2GB at 667MHz', i have recently bought the full quantity of FB-DIMMS from ebay, not had a chance to test it yet, im assuming there are 2 typos in this, one being the extra '1' at '32GB1' and is my math is correct, that would be up to 4GB per slot not 2GB, i have seen some people saying they have 32GB in their T5400 system board... and some saying they couldnt get 32GB in their T5400 system board, can anyone also clarify this? im aware i may need to do a bios update

Thanks for any information in advance

 

[william p]

Dell only lists the spec. of parts they actually tested, or offered for sale from them. It's very common for faster memory or CPUs to run OK. Also Dell doesn't update their spec. sheet when new features are added in a BIOS upgrade. The 150W GPU limit is probably based on what cables the PSU has available. The PSUs in these are very multirail so you can't assume that the 6 pin GPU connectors have as much power as a single rail aftermarket PSU. dell uses yellow, and White wires for 12V. with colored traces for additional rails. You can map out each rail and see what's on it. If you're not using the 2nd CPU then maybe more power is available else where. There may be 6, or 8 pin cables that are there for other purposes so be careful. The T5400 supports a 2nd CPU and memory on a riser card, so with the card the memory capcity doubles.
FB Dimms are very strange indeed. The modules form their own memory bus with controller chips that talk to each other. This produces a lot of extra heat. latency is also high, but bandwidth is good since all the chips run at once. Since the modules have their own controllers you might try running some of the faster FBDIMMs offered for MacPro workstations. They used Intel CPUs and chipsets and since the MB doesn't control the bus you might get lucky. an aftermarket PSU might be difficult. I think the T5400 had some proprietary connectors on the MB.

 

[mnw48]

thanks, so there is a good chance i can install a nice-ish GPU in the system, no awkward power limits on the dell proprietary PSU

the motherboard for this T5400 has no apparent riser card slot, unless it totals about 50pins, both CPU sockets and all 8 DIMM slots are present on the motherboard, i think it was the next model up that had a riser for up to 64GB of ram.
Something isnt quite right with the info provided in this small 2 page PDF, im just going to have to hope for the best, at least im not limited to a 1.5GB VRAM graphics card, the rest i can adapt to, i have 2x identical X5270 chips on the way, this will be more than enough for a secondary gaming system, the cost of a pair of the best qaud cores for Socket 771 was just way too much, thanks for the info

 

[william p]

You're correct about the riser. I searched for t5400 riser but got a t7400 riser result by mistake. The chipset on that supports 1600FSB. The LGA775 333 to 400 fsb pinmod should work if you transpose the LGA771 layout to LGA775 . The locating pins are moved 90*. It has the potential to be a budget Skulltrail with some locked BIOS O/C love.

 

[mnw48]

i wasnt sure what you meant by the socket 775 mod, but after reading it again, yes i was wondering if i could do something similar to do an overclock on the x5270s that are coming, so is it exactly the same as the 771cpu to 775 board mod? i tried googling for this info but 99% was 771-775 modding

 

[william p]

When the 771 to 775 mod works (if the chipset check for Multi Proc CPUs it fails) The mod consists of a tape that fools the MB into thinking there is an LGA775 CPU,and either notching the CPU, or cutting the locating tabs out of the socket. The triangle marked corner is the same. Once this is done done the VID pins and the BSEL pins work the same.
Since you're not doing the conversion you can skip the tape, and socket mod. I would just set theLGA771CPU next to an LGA775 socket and make a mark with a Sharpie where the LGA775 notches would be. I did see a thread on LGA771 CPU pinout. I think LGA771 O/C serach will get you past the LGA775/771 mod. Just remember you're trying to fool the MB pins not the CPU connections. The BSEL mod is simple. You can use Throttlestop software to play with Voltage.. The VID mod varies with what base voltage is set at, and them you find one that's high enough but doesn't require very many trace mods.