Building your own RTX 5090 AI PC still looks cheaper than a Mac Studio on a parts list, but the parts list leaves out most of what you'll actually pay. In late 2026 the biggest hidden cost is the graphics card itself. The RTX 5090 has a US$1,999 launch price but traded at about US$6,500 and up in the US in November. Next come electricity (a 5090 PC drew about 570 W at peak in one review, against about 300 W for an M5 Ultra), your own time as the system integrator and support person, and upgrades. The PC can take a new GPU later; the Mac's memory is fixed the day you buy it. Neither option is cheap. The cheaper one depends on how many hours a day it works, how much memory your models need and who fixes it when it breaks.
What does each option really cost?
| Cost line | DIY RTX 5090 AI PC | Mac Studio M5 Ultra |
|---|---|---|
| Main hardware | RTX 5090: US$1,999 launch MSRP; about US$6,500+ US street price (Nov 2026); not in stock at SourceIT | S$7,999 for 96 GB/1TB (Apple Singapore's list price); about S$16,699 for 256 GB/2TB (calculated from Apple Singapore's upgrade pricing; confirm on apple.com/sg) |
| Rest of the system | About S$4,500–5,500 for CPU, motherboard, 64 GB RAM, SSD, 1,000 W+ power supply, case and cooling (illustrative, our estimate) | Included |
| Memory for AI models | 32 GB on the GPU; slows sharply if a model spills to system RAM | 96 GB, 256 GB or 512 GB unified; about 75% usable by the GPU by default |
| Electricity, 4 h/day at peak | About S$259 a year at 570 W | About S$137 a year at 300 W |
| Electricity, 8 h/day at peak | About S$519 a year | About S$273 a year |
| Electricity, 24/7 at peak | About S$1,556 a year | About S$819 a year (idle only: about S$25) |
| Warranty and support | Separate warranty per component; you diagnose faults and handle each claim | One-year Apple warranty in Singapore; AppleCare+ for Mac runs three years |
| Upgrades | GPU, RAM and storage can be replaced | Memory can't be upgraded after purchase |
Source: NVIDIA (RTX 5090 MSRP); GPU Poet eBay pricing (Nov 2026); MacStories (5090 PC peak 567–577 W); Apple ML Research (M5 Ultra about 300 W peak during LLM inference, 15 Oct 2026); Apple Support 102027 (9 W idle). Electricity is illustrative, at SP Group's Q4 2026 tariff of 31.16¢/kWh including GST, and uses peak figures, so typical bills will be lower. US prices exclude sales tax; Singapore prices include GST.
Why is the graphics card the biggest hidden cost?
Because the launch price no longer means much. Memory and GPU supply have been tight all year, and US street prices for the RTX 5090 rose from about US$4,000 in March 2026 to more than US$6,500 by November. Converting that at today's exchange rate gives over S$8,000 before GST, but that isn't a Singapore price, and local availability is patchy. SourceIT has no RTX 5090 desktop cards in stock; ask us about availability. If you price a DIY build at US$1,999 for the card, your budget will be wrong before you start.
Then there's the rest of the box. A 5090 needs a 1,000 W or larger power supply (NVIDIA's minimum system recommendation), a case with room for a very large card, and good airflow. A Ryzen 9 9950X3D alone is S$1,108.02 at SourceIT (listed 8 Nov 2026; prices change, ask for a current quotation). Our Mac Studio vs RTX 5090 PC comparison covers the performance side of that build.
What about the memory you didn't pay for?
This is the cost most buyers miss. The RTX 5090 has 32 GB of memory. Models that fit run very fast: MacStories measured 59 tokens per second of generation on Qwen3.8-27B, against 48 on an M5 Ultra. When a model doesn't fit and spills into system RAM, MacStories saw the same PC drop to between 1.5 and 4.6 tokens per second. Getting more GPU memory on the PC side means a second card or a professional card, and an RTX PRO 6000 with 96 GB is S$29,100 at SourceIT (listed 8 Nov 2026).
On the Mac, memory is the main cost decision. Apple's Singapore memory upgrades follow roughly 1.5 times the US upgrade steps, and you can't add more later. Buying too little means replacing the whole machine; buying too much means paying for capacity you never use. We discuss how to size it in which ages faster: Mac Studio or RTX Spark.
How much does electricity add in Singapore?
More than people expect for a PC that works all day, and not much for a Mac. At 31.16¢/kWh, every 100 W running around the clock costs about S$273 a year. Using peak figures as a worst case, a 5090 PC at 570 W for eight hours a day costs about S$519 a year to run, and an M5 Ultra at 300 W about S$273. Run both flat out 24/7 and the gap is about S$737 a year. Left idle, the Mac draws about 9 W, or roughly S$25 a year.
These are illustrative numbers. Real draw depends on the model, prompt lengths and how much of the day the machine sits waiting. Air-conditioning load and a UPS add to both. A tower UPS such as the APC Back-UPS Pro 1500VA (865 W) is S$886.25 at SourceIT (listed 8 Nov 2026). For the 5090's power demands in detail, see our RTX 5090 575 W power guide.
A parts list tells you what a computer costs to buy. It doesn't tell you what it costs to own, power, fix and outgrow.
Who maintains and supports each machine?
With a DIY build, you are the integrator. Each component carries its own warranty, so a fault means working out which part failed and claiming it separately while the machine is down. GPU drivers, CUDA versions and AI frameworks need keeping in step. The 5090's 12V-2x6 power connector has to be seated properly (see our 12V-2x6 connector guide). Fans and filters need cleaning. None of this is difficult for an experienced builder, but it is time, and for a business it is staff time.
A Mac Studio has one warranty and one vendor. In Singapore that is a one-year limited warranty. AppleCare+ for Mac extends cover to three years, but we couldn't find Apple Singapore's AppleCare+ price for the Mac Studio. Third-party extended-warranty plans also exist; ask us what cover is available with a SourceIT quotation. The trade-off is repairability. You can't fix a Mac Studio yourself with off-the-shelf parts, and Apple's Self Service Repair parts programme isn't offered in Singapore.
Software support matters too. The PC runs CUDA, so nearly every open-source AI tool works on it. The Mac runs MLX and llama.cpp well, but some CUDA-only tools don't run at all. For a broader view of ownership costs for any AI workstation, see the hidden costs of owning an AI workstation in Singapore.
Which upgrade path costs less over time?
The PC wins on flexibility. You can drop in a newer GPU, add RAM or storage, or sell the 5090 separately if prices stay high. The Mac's upgrade path is replacement. Apple reportedly plans to skip an M6 Ultra and release an M7 Ultra Mac Studio around 2028, according to Bloomberg's Mark Gurman. That suggests a long gap before the next high-end model, though it is a rumour. Historically, Macworld notes that Macs have received around seven to eight years of macOS updates.
The answer depends on what you're optimising for:
- Short daily use, models under about 30 GB, and you enjoy building: a DIY PC gives the fastest results for the money, if you can find a card at a sane price.
- Long daily use, models from 40 GB to several hundred GB, or no in-house support: the Mac's power bill, single warranty and memory capacity usually make it cheaper to own.
- Budget-sensitive: compare both against a smaller build. Our S$5,000 AI PC vs S$15,000 Mac Studio post covers that, and local AI vs cloud API costs asks whether you need the hardware at all.
Buying in Singapore
SourceIT lists the Mac Studio M5 Ultra 96 GB/1TB and M5 Ultra 256 GB/2TB as price on request; ask us for a quotation. RTX 5090 desktop cards aren't in stock, so ask us about availability; other NVIDIA cards are in our NVIDIA graphics cards collection. For DIY builders, the AMD Ryzen 9 9950X3D is S$1,108.02 (listed 8 Nov 2026). Use Request for Quotation on the product page, call (65) 6978 3502, email Sales@sourceit.com.sg or use our contact page.
Frequently asked questions
Is a DIY RTX 5090 PC cheaper than a Mac Studio? Only if you can buy the card near its launch price. At November 2026 US street prices, the card alone converts to more than S$8,000, so a complete 5090 build is likely to cost more than a 96 GB M5 Ultra at S$7,999 (Apple Singapore's list price), before electricity and support.
How much does it cost to run a Mac Studio all day in Singapore? At 31.16¢/kWh, an M5 Ultra running at its roughly 300 W inference peak for eight hours a day costs about S$273 a year. Idle all the time, it costs about S$25 a year.
Can I upgrade a Mac Studio's memory later? No. Memory is part of the Apple chip package and is fixed at purchase, so choose the capacity you'll need for the machine's whole life.
What warranty comes with each option? A Mac Studio has Apple's one-year warranty in Singapore, extendable with AppleCare+ to three years. A DIY PC has a separate warranty for each component, and you handle diagnosis and claims yourself.
Does a DIY PC run more AI software? Generally yes. CUDA support means almost every open-source AI tool runs on an NVIDIA PC. The Mac runs MLX, llama.cpp, LM Studio and Ollama well, but CUDA-only tools need alternatives.
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